Allow a piece of something to be acted on by itself
"18585555555" vs "1"+"8585555555"
Take a piece and give it a name and ablity to reuse via variable or method extraction.
“1” + “858555555” vs areaCode + “858555555”
This is simular to seperate, but does so exposing a calutation undernth. It can also be a conversion (string to int, etc...)
age = 21 vs age = 2020 - 1999 vs age = Date.today.year - 1999
Put something repetative into a loop.
numbers = [5,6,7,8,9,10] vs numbers = [5..10]
Any step refactoring step that makes the code look nicer