1One time you use a comma is when separating phraes that do not need to be there.
Ex:My dog ,Melisa, is very crazy.
2When linking two independent clauses with a conjunction
Ex:I'd like to go to Disney world ,but I have to do my home work .
3When you are addressing some one in particular
Ex: Let's play,Billy.
4When making a list
Ex:We need eggs,dogfood,chips,soda,and candy.
5When you have one or more adjectives
Ex:The great,important, marvelous, Sarah!
6After introducing phraes or clauses
Ex:Once we eat,we will go to the park.
Ex:October 31st ,2013
Ex: Have a good day . Love , dad
9The states and cities
When not to use a comma
1When separating two independent clauses without conjunction .
2After the conjunction.
3Separating a dependent and independent clause with conjunction.