What is an "unlocked cell phone"? What good are they and why buy one?

Question

I am a cyber spud so I NEED help here...

Answer 1

A locked phone would be for example a phone that is set to work with a single service provider (t-mobile or verizon etc...)

An unlocked cell phone is one that you should be able put virtually any SIM card into and use the service associated with it.  If you switch services or are buying a new phone as long as the phone's unlocked you won't have to worry if it's set to work with your SIM card/service provider.