How Do I Know if Its the Battery or Alternator Making the Car Not Crank?

Everytime I try to crank the car it doesn't. I have to jump start it. Sometime when I let it sit it ends up cutting off. I am able to drive it sometime, but when I cut it off it wont start back up. Its an 03 Dodge Stratus

Suggestion:

You can have the battery tested at any part store ot repair shop. If it is the altenator you should have a light on the dashboard on.