What does jailbreaking your iPhone do?

I hear people talk about jailbreaking their iPhone/iPod all the time, but I'm not really sure what that means? What are the benefits of doing this?

Added (1). * If you could also take the time to check out my other question, it would be very much appreciated! Thank you! ↓↓↓

http://answers.yahoo.com/question/index;_ylt=AslNaZc3q4hDpkpfLo364cPsy6IX;_ylv=3?qid=20120807012121AAp9IN3

Well it basically is when you put a software on you i device called cydia. There you can install an app called installous which can let you download free paid apps and perks on your device. I personally don't recommend it because it becomes a little slow. AND it kills you warranty with apple.

It will help your phone to purchase free games
Well it basically is when you put a software on you i device called cydia. There you can install an app called installous which can let you download free paid apps and perks on your device. I personally don't recommend it because it becomes a little slow. AND it kills you warranty with apple.

Think of it as:

Apple restricts what you can and can't do on your iPhone. Jailbreaking removes those limitations, allowing limitless freedom.

Of course, as others have mentioned, it voids your warranty. And if you don't know what you're doing, you can seriously mess up your phone.