SIM cards
 

I want to get a new cell phone, as I have the one that my provider gave me, but it sucks. My question is, would I be able to just buy a new phone and throw my SIM card in the new one? And if the answer is yes, then do all cells accept the same SIM cards? thanks!

SIM is an international standard. you can certainly phone-hop taking your card with you.

Yes you can switch out the SIM card. I have to do it all the time. Sometimes you have to unlock the phone to work for that provider, but generally if you buy your phone off eBay they come unlocked. Just make sure the phone is GSM otherwise it won't work.