diff --git a/app.py b/app.py
index 5a25882..86413cc 100644
--- a/app.py
+++ b/app.py
@@ -1,9 +1,15 @@
 from flask import Flask, render_template, request, redirect, abort, url_for, make_response
+from flask_login import current_user
 from authentication import *
 from db import * 
 import random
 
 app = Flask(__name__)
+login_manager.init_app(app)
+
+# Secret key for login session management, set this up in your .env file 
+load_dotenv()
+app.secret_key = os.getenv("SECRET_KEY")
 
 @app.route("/", methods=["GET", "POST"])
 def home():
@@ -19,20 +25,25 @@ def home():
 # Handle authentication related stuff in authentication.py file
 @app.route('/login', methods=["GET", "POST"])
 def login():
-    return authLogin()
+    return auth_login()
 
 @app.route('/signup', methods=["GET", "POST"])
 def signup():
-    return authSignup()
+    return auth_signup()
 
 @app.route("/<username>/decks")
 def allDecks(username):
-    # would need to first find user in db, but not set up yet
     if username == "guest":
         mainDecks = db.decks.find({})
         return render_template('decks.html', mainDecks=mainDecks)
     else:
-        return "to do: for users"
+        if (not current_user.is_authenticated or current_user.id != username):
+            # TODO: Implement proper 404 screen to redirect here.
+            return username + " needs to log in first."
+        else:
+            # TODO: Redirect to the decks of the current user
+            return "Here would be the decks of " + current_user.id + "."
+
 
 @app.route("/<username>/<deckTitle>")
 def displayDeck(username, deckTitle):
@@ -103,3 +114,4 @@ def deleteDeck(username, deckTitle):
 if __name__ == "__main__":
     FLASK_PORT = os.getenv("FLASK_PORT", "5000")
     app.run(port=FLASK_PORT)
+
diff --git a/authentication.py b/authentication.py
index e76ec9a..1f6a91f 100644
--- a/authentication.py
+++ b/authentication.py
@@ -1,31 +1,75 @@
-from flask import render_template, request, redirect, url_for, session
-from flask_login import LoginManager
+from flask import render_template, request, redirect, url_for, session, flash
+from flask_login import LoginManager, UserMixin, login_user
 from db import *
-
+from pymongo import *
+from werkzeug.security import generate_password_hash, check_password_hash
 
 login_manager = LoginManager()
 
-class User():
-    def __init__(self, username, password, is_authenticated, is_active, is_anonymous):
-        self.is_authenticated = is_authenticated
-        self.is_active = is_active
-        self.is_anonymous = is_anonymous
+'''
+NOTE: 
+To get the active user from a different file or somewhere else 
+you need to import flask_login first then you can retrieve the active user with current_user
+Example:
+    from flask_login import current_user
+    if current_user.is_authenticated:
+        # Do something with current_user
+Also check allDecks function in app.py for example usage
+'''
+# Automatically implements is_authenticated, is_anonymous, is_active and get_id()
+# through UserMixin 
+class User(UserMixin):
+    def __init__(self, user_id, password):
+        self.id = user_id 
+        self.password = password 
+
+    def verify_password(self, pwd):
+        return check_password_hash(self.password, pwd)
+
 
 @login_manager.user_loader
 def load_user(user_id):
-    return User.get(user_id)
+    data = db['users'].find_one({"user_id": user_id})
+    if (data):
+        return User(data['user_id'], data['password'])
+    else:
+        return None
+
 
-def authLogin():
+def auth_login():
+    collections = db.list_collection_names()
     if request.method == 'POST':
-        ## TODO: Login
-        return "Someone pressed the login button huh, I better log you in."
+        user_id = request.form["username"]
+        password = request.form["password"]
+        user = load_user(user_id)
+        if user and user.verify_password(password):
+            # TODO: Redirect to the appropriate page for the logged in user
+            login_user(user)
+            return redirect('/')
+        else:
+            return render_template('login.html', invalid_login=True)
     else:
-        return render_template('login.html')
+        return render_template('login.html', invalid_login=False)
+
 
-def authSignup():
+def auth_signup():
     if request.method == 'POST':
-        username = request.form["username"]
+        user_id = request.form["username"]
         password = request.form["password"]
+        confirm_password =  request.form["confirm-password"]
+        if load_user(user_id):
+            return render_template('signup.html', username_taken=True, passwords_dont_match=False)
+        elif password != confirm_password:
+            return render_template('signup.html', username_taken=False, passwords_dont_match=True)
+        else:
+            user = User(user_id, generate_password_hash(password))
+            db['users'].insert_one({"user_id": user.id, "password": user.password})
+            login_user(user)
+            # TODO: Redirect to the appropriate page for the logged in user
+            return redirect('/')
+
     else:
-        return render_template('signup.html')
+        return render_template('signup.html', username_taken=False, passwords_dont_match=False)
+
+
 
diff --git a/static/css/style.css b/static/css/style.css
index 5a5d1e3..76cca7e 100644
--- a/static/css/style.css
+++ b/static/css/style.css
@@ -116,3 +116,7 @@ h3 {
   justify-content: center;
   align-items: center;
 }
+
+.signup-error, .login-error {
+  font-size: 25px;
+}
diff --git a/templates/login.html b/templates/login.html
index 06b9613..0bc1657 100644
--- a/templates/login.html
+++ b/templates/login.html
@@ -6,6 +6,9 @@
     <form class="vertical-align" action={{url_for('login')}} method="post">
         <input class="user-input" type="username" name="username" placeholder="Username" required>
         <input class="user-input" type="password" name="password" placeholder="Password" required>
+        {% if invalid_login %}
+            <p class="login-error"> Password or username is invalid </p> 
+        {% endif %}
         <input class="button" type="submit" value="Login">
     </form>
 </div>
diff --git a/templates/signup.html b/templates/signup.html
index 03c05d4..d659d7b 100644
--- a/templates/signup.html
+++ b/templates/signup.html
@@ -5,8 +5,14 @@
 <div class="card">
     <form class="vertical-align" action="{{action}}" method="post">
         <input class="user-input" type="username" name="username" placeholder="Username" required>
+        {% if username_taken %}
+            <p class="signup-error"> This username is taken. </p> 
+        {% endif %}
         <input class="user-input" type="password" name="password" placeholder="Password" required>
-        <input class="user-input" type="confirm-password" name="confirm-password" placeholder="Confirm Password" required>
+        <input class="user-input" type="password" name="confirm-password" placeholder="Confirm Password" required>
+        {% if passwords_dont_match %}
+            <p class="signup-error"> The passwords don't match. </p> 
+        {% endif %}
         <input class="button" type="submit" value="Sign Up">
     </form>
 </div>