diff --git a/rdflib/graph.py b/rdflib/graph.py
index 805bb7c64c..4d2fa47bf3 100644
--- a/rdflib/graph.py
+++ b/rdflib/graph.py
@@ -1,4 +1,15 @@
-from typing import Optional, Union, Type, cast, overload, Generator, Tuple
+from typing import (
+    IO,
+    Any,
+    Iterable,
+    Optional,
+    Union,
+    Type,
+    cast,
+    overload,
+    Generator,
+    Tuple,
+)
 import logging
 from warnings import warn
 import random
@@ -21,7 +32,7 @@
 import tempfile
 import pathlib
 
-from io import BytesIO, BufferedIOBase
+from io import BytesIO
 from urllib.parse import urlparse
 
 assert Literal  # avoid warning
@@ -313,15 +324,19 @@ class Graph(Node):
     """
 
     def __init__(
-        self, store="default", identifier=None, namespace_manager=None, base=None
+        self,
+        store: Union[Store, str] = "default",
+        identifier: Optional[Union[Node, str]] = None,
+        namespace_manager: Optional[NamespaceManager] = None,
+        base: Optional[str] = None,
     ):
         super(Graph, self).__init__()
         self.base = base
-        self.__identifier = identifier or BNode()
-
+        self.__identifier: Node
+        self.__identifier = identifier or BNode()  # type: ignore[assignment]
         if not isinstance(self.__identifier, Node):
-            self.__identifier = URIRef(self.__identifier)
-
+            self.__identifier = URIRef(self.__identifier)  # type: ignore[unreachable]
+        self.__store: Store
         if not isinstance(store, Store):
             # TODO: error handling
             self.__store = store = plugin.get(store, Store)()
@@ -404,7 +419,7 @@ def close(self, commit_pending_transaction=False):
         """
         return self.__store.close(commit_pending_transaction=commit_pending_transaction)
 
-    def add(self, triple):
+    def add(self, triple: Tuple[Node, Node, Node]):
         """Add a triple with self as context"""
         s, p, o = triple
         assert isinstance(s, Node), "Subject %s must be an rdflib term" % (s,)
@@ -413,7 +428,7 @@ def add(self, triple):
         self.__store.add((s, p, o), self, quoted=False)
         return self
 
-    def addN(self, quads):
+    def addN(self, quads: Iterable[Tuple[Node, Node, Node, Any]]):
         """Add a sequence of triple with context"""
 
         self.__store.addN(
@@ -434,7 +449,9 @@ def remove(self, triple):
         self.__store.remove(triple, context=self)
         return self
 
-    def triples(self, triple):
+    def triples(
+        self, triple: Tuple[Optional[Node], Union[None, Path, Node], Optional[Node]]
+    ):
         """Generator over the triple store
 
         Returns triples that match the given triple pattern. If triple pattern
@@ -652,17 +669,17 @@ def set(self, triple):
         self.add((subject, predicate, object_))
         return self
 
-    def subjects(self, predicate=None, object=None):
+    def subjects(self, predicate=None, object=None) -> Iterable[Node]:
         """A generator of subjects with the given predicate and object"""
         for s, p, o in self.triples((None, predicate, object)):
             yield s
 
-    def predicates(self, subject=None, object=None):
+    def predicates(self, subject=None, object=None) -> Iterable[Node]:
         """A generator of predicates with the given subject and object"""
         for s, p, o in self.triples((subject, None, object)):
             yield p
 
-    def objects(self, subject=None, predicate=None):
+    def objects(self, subject=None, predicate=None) -> Iterable[Node]:
         """A generator of objects with the given subject and predicate"""
         for s, p, o in self.triples((subject, predicate, None)):
             yield o
@@ -1011,7 +1028,12 @@ def absolutize(self, uri, defrag=1):
     # no destination and non-None positional encoding
     @overload
     def serialize(
-        self, destination: None, format: str, base: Optional[str], encoding: str, **args
+        self,
+        destination: None,
+        format: str,
+        base: Optional[str],
+        encoding: str,
+        **args,
     ) -> bytes:
         ...
 
@@ -1019,45 +1041,32 @@ def serialize(
     @overload
     def serialize(
         self,
-        *,
         destination: None = ...,
         format: str = ...,
         base: Optional[str] = ...,
+        *,
         encoding: str,
         **args,
     ) -> bytes:
         ...
 
-    # no destination and None positional encoding
+    # no destination and None encoding
     @overload
     def serialize(
         self,
-        destination: None,
-        format: str,
-        base: Optional[str],
-        encoding: None,
-        **args,
-    ) -> str:
-        ...
-
-    # no destination and None keyword encoding
-    @overload
-    def serialize(
-        self,
-        *,
         destination: None = ...,
         format: str = ...,
         base: Optional[str] = ...,
-        encoding: None = None,
+        encoding: None = ...,
         **args,
     ) -> str:
         ...
 
-    # non-none destination
+    # non-None destination
     @overload
     def serialize(
         self,
-        destination: Union[str, BufferedIOBase, pathlib.PurePath],
+        destination: Union[str, pathlib.PurePath, IO[bytes]],
         format: str = ...,
         base: Optional[str] = ...,
         encoding: Optional[str] = ...,
@@ -1069,21 +1078,21 @@ def serialize(
     @overload
     def serialize(
         self,
-        destination: Union[str, BufferedIOBase, pathlib.PurePath, None] = None,
-        format: str = "turtle",
-        base: Optional[str] = None,
-        encoding: Optional[str] = None,
+        destination: Optional[Union[str, pathlib.PurePath, IO[bytes]]] = ...,
+        format: str = ...,
+        base: Optional[str] = ...,
+        encoding: Optional[str] = ...,
         **args,
     ) -> Union[bytes, str, "Graph"]:
         ...
 
     def serialize(
         self,
-        destination: Union[str, BufferedIOBase, pathlib.PurePath, None] = None,
+        destination: Optional[Union[str, pathlib.PurePath, IO[bytes]]] = None,
         format: str = "turtle",
         base: Optional[str] = None,
         encoding: Optional[str] = None,
-        **args,
+        **args: Any,
     ) -> Union[bytes, str, "Graph"]:
         """Serialize the Graph to destination
 
@@ -1104,7 +1113,7 @@ def serialize(
             base = self.base
 
         serializer = plugin.get(format, Serializer)(self)
-        stream: BufferedIOBase
+        stream: IO[bytes]
         if destination is None:
             stream = BytesIO()
             if encoding is None:
@@ -1114,7 +1123,7 @@ def serialize(
                 serializer.serialize(stream, base=base, encoding=encoding, **args)
                 return stream.getvalue()
         if hasattr(destination, "write"):
-            stream = cast(BufferedIOBase, destination)
+            stream = cast(IO[bytes], destination)
             serializer.serialize(stream, base=base, encoding=encoding, **args)
         else:
             if isinstance(destination, pathlib.PurePath):
@@ -1149,10 +1158,10 @@ def parse(
         self,
         source=None,
         publicID=None,
-        format=None,
+        format: Optional[str] = None,
         location=None,
         file=None,
-        data=None,
+        data: Optional[Union[str, bytes, bytearray]] = None,
         **args,
     ):
         """
@@ -1537,7 +1546,12 @@ class ConjunctiveGraph(Graph):
     All queries are carried out against the union of all graphs.
     """
 
-    def __init__(self, store="default", identifier=None, default_graph_base=None):
+    def __init__(
+        self,
+        store: Union[Store, str] = "default",
+        identifier: Optional[Union[Node, str]] = None,
+        default_graph_base: Optional[str] = None,
+    ):
         super(ConjunctiveGraph, self).__init__(store, identifier=identifier)
         assert self.store.context_aware, (
             "ConjunctiveGraph must be backed by" " a context aware store."
@@ -1555,7 +1569,31 @@ def __str__(self):
         )
         return pattern % self.store.__class__.__name__
 
-    def _spoc(self, triple_or_quad, default=False):
+    @overload
+    def _spoc(
+        self,
+        triple_or_quad: Union[
+            Tuple[Node, Node, Node, Optional[Any]], Tuple[Node, Node, Node]
+        ],
+        default: bool = False,
+    ) -> Tuple[Node, Node, Node, Optional[Graph]]:
+        ...
+
+    @overload
+    def _spoc(
+        self,
+        triple_or_quad: None,
+        default: bool = False,
+    ) -> Tuple[None, None, None, Optional[Graph]]:
+        ...
+
+    def _spoc(
+        self,
+        triple_or_quad: Optional[
+            Union[Tuple[Node, Node, Node, Optional[Any]], Tuple[Node, Node, Node]]
+        ],
+        default: bool = False,
+    ) -> Tuple[Optional[Node], Optional[Node], Optional[Node], Optional[Graph]]:
         """
         helper method for having methods that support
         either triples or quads
@@ -1564,9 +1602,9 @@ def _spoc(self, triple_or_quad, default=False):
             return (None, None, None, self.default_context if default else None)
         if len(triple_or_quad) == 3:
             c = self.default_context if default else None
-            (s, p, o) = triple_or_quad
+            (s, p, o) = triple_or_quad  # type: ignore[misc]
         elif len(triple_or_quad) == 4:
-            (s, p, o, c) = triple_or_quad
+            (s, p, o, c) = triple_or_quad  # type: ignore[misc]
             c = self._graph(c)
         return s, p, o, c
 
@@ -1577,7 +1615,7 @@ def __contains__(self, triple_or_quad):
             return True
         return False
 
-    def add(self, triple_or_quad):
+    def add(self, triple_or_quad: Union[Tuple[Node, Node, Node, Optional[Any]], Tuple[Node, Node, Node]]) -> "ConjunctiveGraph":  # type: ignore[override]
         """
         Add a triple or quad to the store.
 
@@ -1591,7 +1629,15 @@ def add(self, triple_or_quad):
         self.store.add((s, p, o), context=c, quoted=False)
         return self
 
-    def _graph(self, c):
+    @overload
+    def _graph(self, c: Union[Graph, Node, str]) -> Graph:
+        ...
+
+    @overload
+    def _graph(self, c: None) -> None:
+        ...
+
+    def _graph(self, c: Optional[Union[Graph, Node, str]]) -> Optional[Graph]:
         if c is None:
             return None
         if not isinstance(c, Graph):
@@ -1599,7 +1645,7 @@ def _graph(self, c):
         else:
             return c
 
-    def addN(self, quads):
+    def addN(self, quads: Iterable[Tuple[Node, Node, Node, Any]]):
         """Add a sequence of triples with context"""
 
         self.store.addN(
@@ -1689,13 +1735,19 @@ def contexts(self, triple=None):
             else:
                 yield self.get_context(context)
 
-    def get_context(self, identifier, quoted=False, base=None):
+    def get_context(
+        self,
+        identifier: Optional[Union[Node, str]],
+        quoted: bool = False,
+        base: Optional[str] = None,
+    ) -> Graph:
         """Return a context graph for the given identifier
 
         identifier must be a URIRef or BNode.
         """
+        # TODO: FIXME - why is ConjunctiveGraph passed as namespace_manager?
         return Graph(
-            store=self.store, identifier=identifier, namespace_manager=self, base=base
+            store=self.store, identifier=identifier, namespace_manager=self, base=base  # type: ignore[arg-type]
         )
 
     def remove_context(self, context):
@@ -1747,6 +1799,7 @@ def parse(
         context = Graph(store=self.store, identifier=g_id)
         context.remove((None, None, None))  # hmm ?
         context.parse(source, publicID=publicID, format=format, **args)
+        # TODO: FIXME: This should not return context, but self.
         return context
 
     def __reduce__(self):
@@ -1977,7 +2030,7 @@ class QuotedGraph(Graph):
     def __init__(self, store, identifier):
         super(QuotedGraph, self).__init__(store, identifier)
 
-    def add(self, triple):
+    def add(self, triple: Tuple[Node, Node, Node]):
         """Add a triple with self as context"""
         s, p, o = triple
         assert isinstance(s, Node), "Subject %s must be an rdflib term" % (s,)
@@ -1987,7 +2040,7 @@ def add(self, triple):
         self.store.add((s, p, o), self, quoted=True)
         return self
 
-    def addN(self, quads):
+    def addN(self, quads: Tuple[Node, Node, Node, Any]) -> "QuotedGraph":  # type: ignore[override]
         """Add a sequence of triple with context"""
 
         self.store.addN(
@@ -2261,7 +2314,7 @@ class BatchAddGraph(object):
 
     """
 
-    def __init__(self, graph, batch_size=1000, batch_addn=False):
+    def __init__(self, graph: Graph, batch_size: int = 1000, batch_addn: bool = False):
         if not batch_size or batch_size < 2:
             raise ValueError("batch_size must be a positive number")
         self.graph = graph
@@ -2278,7 +2331,10 @@ def reset(self):
         self.count = 0
         return self
 
-    def add(self, triple_or_quad):
+    def add(
+        self,
+        triple_or_quad: Union[Tuple[Node, Node, Node], Tuple[Node, Node, Node, Any]],
+    ) -> "BatchAddGraph":
         """
         Add a triple to the buffer
 
@@ -2294,7 +2350,7 @@ def add(self, triple_or_quad):
             self.batch.append(triple_or_quad)
         return self
 
-    def addN(self, quads):
+    def addN(self, quads: Iterable[Tuple[Node, Node, Node, Any]]):
         if self.__batch_addn:
             for q in quads:
                 self.add(q)
diff --git a/rdflib/parser.py b/rdflib/parser.py
index f0014150f6..1f8a490cde 100644
--- a/rdflib/parser.py
+++ b/rdflib/parser.py
@@ -16,6 +16,7 @@
 import sys
 
 from io import BytesIO, TextIOBase, TextIOWrapper, StringIO, BufferedIOBase
+from typing import Optional, Union
 
 from urllib.request import Request
 from urllib.request import url2pathname
@@ -44,7 +45,7 @@ class Parser(object):
     def __init__(self):
         pass
 
-    def parse(self, source, sink):
+    def parse(self, source, sink, **args):
         pass
 
 
@@ -214,7 +215,12 @@ def __repr__(self):
 
 
 def create_input_source(
-    source=None, publicID=None, location=None, file=None, data=None, format=None
+    source=None,
+    publicID=None,
+    location=None,
+    file=None,
+    data: Optional[Union[str, bytes, bytearray]] = None,
+    format=None,
 ):
     """
     Return an appropriate InputSource instance for the given
diff --git a/rdflib/plugin.py b/rdflib/plugin.py
index 719c7eaf55..ac3a7fbd06 100644
--- a/rdflib/plugin.py
+++ b/rdflib/plugin.py
@@ -36,7 +36,21 @@
     UpdateProcessor,
 )
 from rdflib.exceptions import Error
-from typing import Type, TypeVar
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Dict,
+    Generic,
+    Iterator,
+    Optional,
+    Tuple,
+    Type,
+    TypeVar,
+    overload,
+)
+
+if TYPE_CHECKING:
+    from pkg_resources import EntryPoint
 
 __all__ = ["register", "get", "plugins", "PluginException", "Plugin", "PKGPlugin"]
 
@@ -51,42 +65,47 @@
     "rdf.plugins.updateprocessor": UpdateProcessor,
 }
 
-_plugins = {}
+_plugins: Dict[Tuple[str, Type[Any]], "Plugin"] = {}
 
 
 class PluginException(Error):
     pass
 
 
-class Plugin(object):
-    def __init__(self, name, kind, module_path, class_name):
+PluginT = TypeVar("PluginT")
+
+
+class Plugin(Generic[PluginT]):
+    def __init__(
+        self, name: str, kind: Type[PluginT], module_path: str, class_name: str
+    ):
         self.name = name
         self.kind = kind
         self.module_path = module_path
         self.class_name = class_name
-        self._class = None
+        self._class: Optional[Type[PluginT]] = None
 
-    def getClass(self):
+    def getClass(self) -> Type[PluginT]:
         if self._class is None:
             module = __import__(self.module_path, globals(), locals(), [""])
             self._class = getattr(module, self.class_name)
         return self._class
 
 
-class PKGPlugin(Plugin):
-    def __init__(self, name, kind, ep):
+class PKGPlugin(Plugin[PluginT]):
+    def __init__(self, name: str, kind: Type[PluginT], ep: "EntryPoint"):
         self.name = name
         self.kind = kind
         self.ep = ep
-        self._class = None
+        self._class: Optional[Type[PluginT]] = None
 
-    def getClass(self):
+    def getClass(self) -> Type[PluginT]:
         if self._class is None:
             self._class = self.ep.load()
         return self._class
 
 
-def register(name: str, kind, module_path, class_name):
+def register(name: str, kind: Type[Any], module_path, class_name):
     """
     Register the plugin for (name, kind). The module_path and
     class_name should be the path to a plugin class.
@@ -95,16 +114,13 @@ def register(name: str, kind, module_path, class_name):
     _plugins[(name, kind)] = p
 
 
-PluginT = TypeVar("PluginT")
-
-
 def get(name: str, kind: Type[PluginT]) -> Type[PluginT]:
     """
     Return the class for the specified (name, kind). Raises a
     PluginException if unable to do so.
     """
     try:
-        p = _plugins[(name, kind)]
+        p: Plugin[PluginT] = _plugins[(name, kind)]
     except KeyError:
         raise PluginException("No plugin registered for (%s, %s)" % (name, kind))
     return p.getClass()
@@ -121,7 +137,21 @@ def get(name: str, kind: Type[PluginT]) -> Type[PluginT]:
             _plugins[(ep.name, kind)] = PKGPlugin(ep.name, kind, ep)
 
 
-def plugins(name=None, kind=None):
+@overload
+def plugins(
+    name: Optional[str] = ..., kind: Type[PluginT] = ...
+) -> Iterator[Plugin[PluginT]]:
+    ...
+
+
+@overload
+def plugins(name: Optional[str] = ..., kind: None = ...) -> Iterator[Plugin]:
+    ...
+
+
+def plugins(
+    name: Optional[str] = None, kind: Optional[Type[PluginT]] = None
+) -> Iterator[Plugin]:
     """
     A generator of the plugins.
 
diff --git a/rdflib/plugins/serializers/jsonld.py b/rdflib/plugins/serializers/jsonld.py
index 67f3b86232..f5067e2873 100644
--- a/rdflib/plugins/serializers/jsonld.py
+++ b/rdflib/plugins/serializers/jsonld.py
@@ -41,6 +41,7 @@
 from rdflib.graph import Graph
 from rdflib.term import URIRef, Literal, BNode
 from rdflib.namespace import RDF, XSD
+from typing import IO, Optional
 
 from ..shared.jsonld.context import Context, UNDEF
 from ..shared.jsonld.util import json
@@ -53,10 +54,16 @@
 
 
 class JsonLDSerializer(Serializer):
-    def __init__(self, store):
+    def __init__(self, store: Graph):
         super(JsonLDSerializer, self).__init__(store)
 
-    def serialize(self, stream, base=None, encoding=None, **kwargs):
+    def serialize(
+        self,
+        stream: IO[bytes],
+        base: Optional[str] = None,
+        encoding: Optional[str] = None,
+        **kwargs
+    ):
         # TODO: docstring w. args and return value
         encoding = encoding or "utf-8"
         if encoding not in ("utf-8", "utf-16"):
diff --git a/rdflib/plugins/serializers/n3.py b/rdflib/plugins/serializers/n3.py
index 6c4e2ec46d..806f445ef8 100644
--- a/rdflib/plugins/serializers/n3.py
+++ b/rdflib/plugins/serializers/n3.py
@@ -14,7 +14,7 @@ class N3Serializer(TurtleSerializer):
 
     short_name = "n3"
 
-    def __init__(self, store, parent=None):
+    def __init__(self, store: Graph, parent=None):
         super(N3Serializer, self).__init__(store)
         self.keywords.update({OWL.sameAs: "=", SWAP_LOG.implies: "=>"})
         self.parent = parent
diff --git a/rdflib/plugins/serializers/nquads.py b/rdflib/plugins/serializers/nquads.py
index 54ee42ba12..e76c747d49 100644
--- a/rdflib/plugins/serializers/nquads.py
+++ b/rdflib/plugins/serializers/nquads.py
@@ -1,5 +1,7 @@
+from typing import IO, Optional
 import warnings
 
+from rdflib.graph import ConjunctiveGraph, Graph
 from rdflib.term import Literal
 from rdflib.serializer import Serializer
 
@@ -9,15 +11,22 @@
 
 
 class NQuadsSerializer(Serializer):
-    def __init__(self, store):
+    def __init__(self, store: Graph):
         if not store.context_aware:
             raise Exception(
                 "NQuads serialization only makes " "sense for context-aware stores!"
             )
 
         super(NQuadsSerializer, self).__init__(store)
-
-    def serialize(self, stream, base=None, encoding=None, **args):
+        self.store: ConjunctiveGraph
+
+    def serialize(
+        self,
+        stream: IO[bytes],
+        base: Optional[str] = None,
+        encoding: Optional[str] = None,
+        **args
+    ):
         if base is not None:
             warnings.warn("NQuadsSerializer does not support base.")
         if encoding is not None and encoding.lower() != self.encoding.lower():
diff --git a/rdflib/plugins/serializers/nt.py b/rdflib/plugins/serializers/nt.py
index bc265ee5f4..467de46134 100644
--- a/rdflib/plugins/serializers/nt.py
+++ b/rdflib/plugins/serializers/nt.py
@@ -3,6 +3,9 @@
 See <http://www.w3.org/TR/rdf-testcases/#ntriples> for details about the
 format.
 """
+from typing import IO, Optional
+
+from rdflib.graph import Graph
 from rdflib.term import Literal
 from rdflib.serializer import Serializer
 
@@ -17,11 +20,17 @@ class NTSerializer(Serializer):
     Serializes RDF graphs to NTriples format.
     """
 
-    def __init__(self, store):
+    def __init__(self, store: Graph):
         Serializer.__init__(self, store)
         self.encoding = "ascii"  # n-triples are ascii encoded
 
-    def serialize(self, stream, base=None, encoding=None, **args):
+    def serialize(
+        self,
+        stream: IO[bytes],
+        base: Optional[str] = None,
+        encoding: Optional[str] = None,
+        **args
+    ):
         if base is not None:
             warnings.warn("NTSerializer does not support base.")
         if encoding is not None and encoding.lower() != self.encoding.lower():
@@ -39,7 +48,7 @@ class NT11Serializer(NTSerializer):
     Exactly like nt - only utf8 encoded.
     """
 
-    def __init__(self, store):
+    def __init__(self, store: Graph):
         Serializer.__init__(self, store)  # default to utf-8
 
 
diff --git a/rdflib/plugins/serializers/rdfxml.py b/rdflib/plugins/serializers/rdfxml.py
index 72648afbac..901d911d91 100644
--- a/rdflib/plugins/serializers/rdfxml.py
+++ b/rdflib/plugins/serializers/rdfxml.py
@@ -1,9 +1,11 @@
+from typing import IO, Dict, Optional, Set, cast
 from rdflib.plugins.serializers.xmlwriter import XMLWriter
 
 from rdflib.namespace import Namespace, RDF, RDFS  # , split_uri
 from rdflib.plugins.parsers.RDFVOC import RDFVOC
 
-from rdflib.term import URIRef, Literal, BNode
+from rdflib.graph import Graph
+from rdflib.term import Identifier, URIRef, Literal, BNode
 from rdflib.util import first, more_than
 from rdflib.collection import Collection
 from rdflib.serializer import Serializer
@@ -17,7 +19,7 @@
 
 
 class XMLSerializer(Serializer):
-    def __init__(self, store):
+    def __init__(self, store: Graph):
         super(XMLSerializer, self).__init__(store)
 
     def __bindings(self):
@@ -39,14 +41,20 @@ def __bindings(self):
         for prefix, namespace in bindings.items():
             yield prefix, namespace
 
-    def serialize(self, stream, base=None, encoding=None, **args):
+    def serialize(
+        self,
+        stream: IO[bytes],
+        base: Optional[str] = None,
+        encoding: Optional[str] = None,
+        **args
+    ):
         # if base is given here, use that, if not and a base is set for the graph use that
         if base is not None:
             self.base = base
         elif self.store.base is not None:
             self.base = self.store.base
         self.__stream = stream
-        self.__serialized = {}
+        self.__serialized: Dict[Identifier, int] = {}
         encoding = self.encoding
         self.write = write = lambda uni: stream.write(uni.encode(encoding, "replace"))
 
@@ -154,12 +162,18 @@ def fix(val):
 
 
 class PrettyXMLSerializer(Serializer):
-    def __init__(self, store, max_depth=3):
+    def __init__(self, store: Graph, max_depth=3):
         super(PrettyXMLSerializer, self).__init__(store)
-        self.forceRDFAbout = set()
-
-    def serialize(self, stream, base=None, encoding=None, **args):
-        self.__serialized = {}
+        self.forceRDFAbout: Set[URIRef] = set()
+
+    def serialize(
+        self,
+        stream: IO[bytes],
+        base: Optional[str] = None,
+        encoding: Optional[str] = None,
+        **args
+    ):
+        self.__serialized: Dict[Identifier, int] = {}
         store = self.store
         # if base is given here, use that, if not and a base is set for the graph use that
         if base is not None:
@@ -190,8 +204,9 @@ def serialize(self, stream, base=None, encoding=None, **args):
 
         writer.namespaces(namespaces.items())
 
+        subject: Identifier
         # Write out subjects that can not be inline
-        for subject in store.subjects():
+        for subject in store.subjects():  # type: ignore[assignment]
             if (None, None, subject) in store:
                 if (subject, None, subject) in store:
                     self.subject(subject, 1)
@@ -202,7 +217,7 @@ def serialize(self, stream, base=None, encoding=None, **args):
         # write out BNodes last (to ensure they can be inlined where possible)
         bnodes = set()
 
-        for subject in store.subjects():
+        for subject in store.subjects():  # type: ignore[assignment]
             if isinstance(subject, BNode):
                 bnodes.add(subject)
                 continue
@@ -217,9 +232,9 @@ def serialize(self, stream, base=None, encoding=None, **args):
         stream.write("\n".encode("latin-1"))
 
         # Set to None so that the memory can get garbage collected.
-        self.__serialized = None
+        self.__serialized = None  # type: ignore[assignment]
 
-    def subject(self, subject, depth=1):
+    def subject(self, subject: Identifier, depth: int = 1):
         store = self.store
         writer = self.writer
 
@@ -227,7 +242,7 @@ def subject(self, subject, depth=1):
             writer.push(RDFVOC.Description)
             writer.attribute(RDFVOC.about, self.relativize(subject))
             writer.pop(RDFVOC.Description)
-            self.forceRDFAbout.remove(subject)
+            self.forceRDFAbout.remove(subject)  # type: ignore[arg-type]
 
         elif subject not in self.__serialized:
             self.__serialized[subject] = 1
@@ -264,10 +279,11 @@ def subj_as_obj_more_than(ceil):
             writer.pop(element)
 
         elif subject in self.forceRDFAbout:
+            # TODO FIXME?: this looks like a duplicate of first condition
             writer.push(RDFVOC.Description)
             writer.attribute(RDFVOC.about, self.relativize(subject))
             writer.pop(RDFVOC.Description)
-            self.forceRDFAbout.remove(subject)
+            self.forceRDFAbout.remove(subject)  # type: ignore[arg-type]
 
     def predicate(self, predicate, object, depth=1):
         writer = self.writer
diff --git a/rdflib/plugins/serializers/trig.py b/rdflib/plugins/serializers/trig.py
index cdaedd4892..5a606e401c 100644
--- a/rdflib/plugins/serializers/trig.py
+++ b/rdflib/plugins/serializers/trig.py
@@ -4,9 +4,12 @@
 """
 
 from collections import defaultdict
+from typing import IO, TYPE_CHECKING, Optional, Union
 
+from rdflib.graph import ConjunctiveGraph, Graph
 from rdflib.plugins.serializers.turtle import TurtleSerializer
-from rdflib.term import BNode
+from rdflib.term import BNode, Node
+
 
 __all__ = ["TrigSerializer"]
 
@@ -16,8 +19,11 @@ class TrigSerializer(TurtleSerializer):
     short_name = "trig"
     indentString = 4 * " "
 
-    def __init__(self, store):
+    def __init__(self, store: Union[Graph, ConjunctiveGraph]):
+        self.default_context: Optional[Node]
         if store.context_aware:
+            if TYPE_CHECKING:
+                assert isinstance(store, ConjunctiveGraph)
             self.contexts = list(store.contexts())
             self.default_context = store.default_context.identifier
             if store.default_context:
@@ -48,7 +54,14 @@ def reset(self):
         super(TrigSerializer, self).reset()
         self._contexts = {}
 
-    def serialize(self, stream, base=None, encoding=None, spacious=None, **args):
+    def serialize(
+        self,
+        stream: IO[bytes],
+        base: Optional[str] = None,
+        encoding: Optional[str] = None,
+        spacious: Optional[bool] = None,
+        **args
+    ):
         self.reset()
         self.stream = stream
         # if base is given here, use that, if not and a base is set for the graph use that
diff --git a/rdflib/plugins/serializers/trix.py b/rdflib/plugins/serializers/trix.py
index 05b6f528f3..1612d815cc 100644
--- a/rdflib/plugins/serializers/trix.py
+++ b/rdflib/plugins/serializers/trix.py
@@ -1,3 +1,4 @@
+from typing import IO, Optional
 from rdflib.serializer import Serializer
 from rdflib.plugins.serializers.xmlwriter import XMLWriter
 
@@ -15,14 +16,20 @@
 
 
 class TriXSerializer(Serializer):
-    def __init__(self, store):
+    def __init__(self, store: Graph):
         super(TriXSerializer, self).__init__(store)
         if not store.context_aware:
             raise Exception(
                 "TriX serialization only makes sense for context-aware stores"
             )
 
-    def serialize(self, stream, base=None, encoding=None, **args):
+    def serialize(
+        self,
+        stream: IO[bytes],
+        base: Optional[str] = None,
+        encoding: Optional[str] = None,
+        **args
+    ):
 
         nm = self.store.namespace_manager
 
diff --git a/rdflib/plugins/sparql/results/csvresults.py b/rdflib/plugins/sparql/results/csvresults.py
index c87b6ea760..11a0b38165 100644
--- a/rdflib/plugins/sparql/results/csvresults.py
+++ b/rdflib/plugins/sparql/results/csvresults.py
@@ -9,6 +9,7 @@
 
 import codecs
 import csv
+from typing import IO
 
 from rdflib import Variable, BNode, URIRef, Literal
 
@@ -61,7 +62,7 @@ def __init__(self, result):
         if result.type != "SELECT":
             raise Exception("CSVSerializer can only serialize select query results")
 
-    def serialize(self, stream, encoding="utf-8", **kwargs):
+    def serialize(self, stream: IO, encoding: str = "utf-8", **kwargs):
 
         # the serialiser writes bytes in the given encoding
         # in py3 csv.writer is unicode aware and writes STRINGS,
@@ -69,15 +70,15 @@ def serialize(self, stream, encoding="utf-8", **kwargs):
 
         import codecs
 
-        stream = codecs.getwriter(encoding)(stream)
+        stream = codecs.getwriter(encoding)(stream)  # type: ignore[assignment]
 
         out = csv.writer(stream, delimiter=self.delim)
 
-        vs = [self.serializeTerm(v, encoding) for v in self.result.vars]
+        vs = [self.serializeTerm(v, encoding) for v in self.result.vars]  # type: ignore[union-attr]
         out.writerow(vs)
         for row in self.result.bindings:
             out.writerow(
-                [self.serializeTerm(row.get(v), encoding) for v in self.result.vars]
+                [self.serializeTerm(row.get(v), encoding) for v in self.result.vars]  # type: ignore[union-attr]
             )
 
     def serializeTerm(self, term, encoding):
diff --git a/rdflib/plugins/sparql/results/jsonresults.py b/rdflib/plugins/sparql/results/jsonresults.py
index 13a8da5eff..8ae67786a4 100644
--- a/rdflib/plugins/sparql/results/jsonresults.py
+++ b/rdflib/plugins/sparql/results/jsonresults.py
@@ -1,4 +1,5 @@
 import json
+from typing import IO, Any, Dict, Optional, TextIO, Union
 
 from rdflib.query import Result, ResultException, ResultSerializer, ResultParser
 from rdflib import Literal, URIRef, BNode, Variable
@@ -28,9 +29,9 @@ class JSONResultSerializer(ResultSerializer):
     def __init__(self, result):
         ResultSerializer.__init__(self, result)
 
-    def serialize(self, stream, encoding=None):
+    def serialize(self, stream: IO, encoding: str = None, **kwargs):
 
-        res = {}
+        res: Dict[str, Any] = {}
         if self.result.type == "ASK":
             res["head"] = {}
             res["boolean"] = self.result.askAnswer
diff --git a/rdflib/plugins/sparql/results/txtresults.py b/rdflib/plugins/sparql/results/txtresults.py
index baa5316b48..3f41df9429 100644
--- a/rdflib/plugins/sparql/results/txtresults.py
+++ b/rdflib/plugins/sparql/results/txtresults.py
@@ -1,8 +1,11 @@
+from typing import IO, List, Optional
 from rdflib import URIRef, BNode, Literal
 from rdflib.query import ResultSerializer
+from rdflib.namespace import NamespaceManager
+from rdflib.term import Variable
 
 
-def _termString(t, namespace_manager):
+def _termString(t, namespace_manager: Optional[NamespaceManager]):
     if t is None:
         return "-"
     if namespace_manager:
@@ -21,7 +24,13 @@ class TXTResultSerializer(ResultSerializer):
     A write only QueryResult serializer for text/ascii tables
     """
 
-    def serialize(self, stream, encoding, namespace_manager=None):
+    # TODO FIXME: class specific args should be keyword only.
+    def serialize(  # type: ignore[override]
+        self,
+        stream: IO,
+        encoding: str,
+        namespace_manager: Optional[NamespaceManager] = None,
+    ):
         """
         return a text table of query results
         """
@@ -43,7 +52,7 @@ def c(s, w):
             return "(no results)\n"
         else:
 
-            keys = self.result.vars
+            keys: List[Variable] = self.result.vars  # type: ignore[assignment]
             maxlen = [0] * len(keys)
             b = [
                 [_termString(r[k], namespace_manager) for k in keys]
diff --git a/rdflib/plugins/sparql/results/xmlresults.py b/rdflib/plugins/sparql/results/xmlresults.py
index 8c77b50ad1..3869bc9e24 100644
--- a/rdflib/plugins/sparql/results/xmlresults.py
+++ b/rdflib/plugins/sparql/results/xmlresults.py
@@ -1,4 +1,5 @@
 import logging
+from typing import IO, Optional
 
 from xml.sax.saxutils import XMLGenerator
 from xml.dom import XML_NAMESPACE
@@ -28,15 +29,17 @@
 
 
 class XMLResultParser(ResultParser):
-    def parse(self, source, content_type=None):
+    # TODO FIXME: content_type should be a keyword only arg.
+    def parse(self, source, content_type: Optional[str] = None):  # type: ignore[override]
         return XMLResult(source)
 
 
 class XMLResult(Result):
-    def __init__(self, source, content_type=None):
+    def __init__(self, source, content_type: Optional[str] = None):
 
         try:
-            parser = etree.XMLParser(huge_tree=True)
+            # try use as if etree is from lxml, and if not use it as normal.
+            parser = etree.XMLParser(huge_tree=True)  # type: ignore[call-arg]
             tree = etree.parse(source, parser)
         except TypeError:
             tree = etree.parse(source)
@@ -55,7 +58,7 @@ def __init__(self, source, content_type=None):
 
         if type_ == "SELECT":
             self.bindings = []
-            for result in results:
+            for result in results:  # type: ignore[union-attr]
                 r = {}
                 for binding in result:
                     r[Variable(binding.get("name"))] = parseTerm(binding[0])
@@ -69,7 +72,7 @@ def __init__(self, source, content_type=None):
             ]
 
         else:
-            self.askAnswer = boolean.text.lower().strip() == "true"
+            self.askAnswer = boolean.text.lower().strip() == "true"  # type: ignore[union-attr]
 
 
 def parseTerm(element):
@@ -101,7 +104,7 @@ class XMLResultSerializer(ResultSerializer):
     def __init__(self, result):
         ResultSerializer.__init__(self, result)
 
-    def serialize(self, stream, encoding="utf-8"):
+    def serialize(self, stream: IO, encoding: str = "utf-8", **kwargs):
 
         writer = SPARQLXMLWriter(stream, encoding)
         if self.result.type == "ASK":
diff --git a/rdflib/query.py b/rdflib/query.py
index da174cd1f2..65ee141581 100644
--- a/rdflib/query.py
+++ b/rdflib/query.py
@@ -5,6 +5,7 @@
 import warnings
 import types
 from typing import Optional, Union, cast
+from typing import IO, TYPE_CHECKING, List, Optional, TextIO, Union, cast, overload
 
 from io import BytesIO, BufferedIOBase
 
@@ -12,6 +13,10 @@
 
 __all__ = ["Processor", "Result", "ResultParser", "ResultSerializer", "ResultException"]
 
+if TYPE_CHECKING:
+    from .graph import Graph
+    from .term import Variable
+
 
 class Processor(object):
     """
@@ -161,17 +166,17 @@ class Result(object):
 
     """
 
-    def __init__(self, type_):
+    def __init__(self, type_: str):
 
         if type_ not in ("CONSTRUCT", "DESCRIBE", "SELECT", "ASK"):
             raise ResultException("Unknown Result type: %s" % type_)
 
         self.type = type_
-        self.vars = None
+        self.vars: Optional[List[Variable]] = None
         self._bindings = None
         self._genbindings = None
-        self.askAnswer = None
-        self.graph = None
+        self.askAnswer: bool = None  # type: ignore[assignment]
+        self.graph: "Graph" = None  # type: ignore[assignment]
 
     def _get_bindings(self):
         if self._genbindings:
@@ -192,7 +197,12 @@ def _set_bindings(self, b):
     )
 
     @staticmethod
-    def parse(source=None, format=None, content_type=None, **kwargs):
+    def parse(
+        source=None,
+        format: Optional[str] = None,
+        content_type: Optional[str] = None,
+        **kwargs,
+    ):
         from rdflib import plugin
 
         if format:
@@ -208,7 +218,7 @@ def parse(source=None, format=None, content_type=None, **kwargs):
 
     def serialize(
         self,
-        destination: Optional[Union[str, BufferedIOBase]] = None,
+        destination: Optional[Union[str, IO]] = None,
         encoding: str = "utf-8",
         format: str = "xml",
         **args,
@@ -230,7 +240,7 @@ def serialize(
         :return: bytes
         """
         if self.type in ("CONSTRUCT", "DESCRIBE"):
-            return self.graph.serialize(
+            return self.graph.serialize(  # type: ignore[return-value]
                 destination, encoding=encoding, format=format, **args
             )
 
@@ -241,10 +251,10 @@ def serialize(
         if destination is None:
             streamb: BytesIO = BytesIO()
             stream2 = EncodeOnlyUnicode(streamb)
-            serializer.serialize(stream2, encoding=encoding, **args)
+            serializer.serialize(stream2, encoding=encoding, **args)  # type: ignore
             return streamb.getvalue()
         if hasattr(destination, "write"):
-            stream = cast(BufferedIOBase, destination)
+            stream = cast(IO[bytes], destination)
             serializer.serialize(stream, encoding=encoding, **args)
         else:
             location = cast(str, destination)
@@ -339,9 +349,14 @@ def parse(self, source, **kwargs):
 
 
 class ResultSerializer(object):
-    def __init__(self, result):
+    def __init__(self, result: Result):
         self.result = result
 
-    def serialize(self, stream, encoding="utf-8", **kwargs):
+    def serialize(
+        self,
+        stream: IO,
+        encoding: str = "utf-8",
+        **kwargs,
+    ):
         """return a string properly serialized"""
         pass  # abstract
diff --git a/rdflib/serializer.py b/rdflib/serializer.py
index ecb8da0a2b..16a47d55cd 100644
--- a/rdflib/serializer.py
+++ b/rdflib/serializer.py
@@ -10,21 +10,31 @@
 
 """
 
+from typing import IO, TYPE_CHECKING, Optional
 from rdflib.term import URIRef
 
+if TYPE_CHECKING:
+    from rdflib.graph import Graph
+
 __all__ = ["Serializer"]
 
 
-class Serializer(object):
-    def __init__(self, store):
-        self.store = store
-        self.encoding = "UTF-8"
-        self.base = None
+class Serializer:
+    def __init__(self, store: "Graph"):
+        self.store: "Graph" = store
+        self.encoding: str = "UTF-8"
+        self.base: Optional[str] = None
 
-    def serialize(self, stream, base=None, encoding=None, **args):
+    def serialize(
+        self,
+        stream: IO[bytes],
+        base: Optional[str] = None,
+        encoding: Optional[str] = None,
+        **args
+    ) -> None:
         """Abstract method"""
 
-    def relativize(self, uri):
+    def relativize(self, uri: str):
         base = self.base
         if base is not None and uri.startswith(base):
             uri = URIRef(uri.replace(base, "", 1))
diff --git a/rdflib/store.py b/rdflib/store.py
index a7aa8d0b09..d96f569eaf 100644
--- a/rdflib/store.py
+++ b/rdflib/store.py
@@ -1,6 +1,11 @@
 from io import BytesIO
 import pickle
 from rdflib.events import Dispatcher, Event
+from typing import Tuple, TYPE_CHECKING, Iterable, Optional
+
+if TYPE_CHECKING:
+    from .term import Node
+    from .graph import Graph
 
 """
 ============
@@ -172,7 +177,7 @@ def __get_node_pickler(self):
     def create(self, configuration):
         self.dispatcher.dispatch(StoreCreatedEvent(configuration=configuration))
 
-    def open(self, configuration, create=False):
+    def open(self, configuration, create: bool = False):
         """
         Opens the store specified by the configuration string. If
         create is True a store will be created if it does not already
@@ -204,7 +209,12 @@ def gc(self):
         pass
 
     # RDF APIs
-    def add(self, triple, context, quoted=False):
+    def add(
+        self,
+        triple: Tuple["Node", "Node", "Node"],
+        context: Optional["Graph"],
+        quoted: bool = False,
+    ):
         """
         Adds the given statement to a specific context or to the model. The
         quoted argument is interpreted by formula-aware stores to indicate
@@ -215,7 +225,7 @@ def add(self, triple, context, quoted=False):
         """
         self.dispatcher.dispatch(TripleAddedEvent(triple=triple, context=context))
 
-    def addN(self, quads):
+    def addN(self, quads: Iterable[Tuple["Node", "Node", "Node", "Graph"]]):
         """
         Adds each item in the list of statements to a specific context. The
         quoted argument is interpreted by formula-aware stores to indicate this
@@ -283,7 +293,11 @@ def triples_choices(self, triple, context=None):
                 for (s1, p1, o1), cg in self.triples((subject, None, object_), context):
                     yield (s1, p1, o1), cg
 
-    def triples(self, triple_pattern, context=None):
+    def triples(
+        self,
+        triple_pattern: Tuple[Optional["Node"], Optional["Node"], Optional["Node"]],
+        context=None,
+    ):
         """
         A generator over all the triples matching the pattern. Pattern can
         include any objects for used for comparing against nodes in the store,
diff --git a/rdflib/term.py b/rdflib/term.py
index eb1f2cb6ca..837e4a726e 100644
--- a/rdflib/term.py
+++ b/rdflib/term.py
@@ -64,7 +64,7 @@
 from urllib.parse import urlparse
 
 from decimal import Decimal
-from typing import TYPE_CHECKING, Dict, Callable, Union, Type
+from typing import TYPE_CHECKING, Dict, Callable, Optional, Union, Type
 
 if TYPE_CHECKING:
     from .paths import AlternativePath, InvPath, NegatedPath, SequencePath, Path
@@ -231,10 +231,10 @@ class URIRef(Identifier):
     __neg__: Callable[["URIRef"], "NegatedPath"]
     __truediv__: Callable[["URIRef", Union["URIRef", "Path"]], "SequencePath"]
 
-    def __new__(cls, value, base=None):
+    def __new__(cls, value: str, base: Optional[str] = None):
         if base is not None:
             ends_in_hash = value.endswith("#")
-            value = urljoin(base, value, allow_fragments=1)
+            value = urljoin(base, value, allow_fragments=True)
             if ends_in_hash:
                 if not value.endswith("#"):
                     value += "#"
@@ -248,7 +248,7 @@ def __new__(cls, value, base=None):
         try:
             rt = str.__new__(cls, value)
         except UnicodeDecodeError:
-            rt = str.__new__(cls, value, "utf-8")
+            rt = str.__new__(cls, value, "utf-8")  # type: ignore[call-overload]
         return rt
 
     def toPython(self):