Hey, I was wondering if anyone here can help me out.. I got a LG Optimus 2X. The problem is, how do I exit programs/apps on the phone? Some of them don't have the exit buttons..

For example, the music player, if I played a song and now I want to go back to my home screen, do I just press the home button? or back button?

I've come across something about android phone will shut down the apps after a while.. Is that true?