What happens if you jailbreak an iPhone?

What happens if you jailbreak an iPhone? - 1

You install the Cydia app which allows you to install unofficial apps
Jail-breaking is simply allowing certain apps to access files (eg the phone boot animation) that the apps normally couldn't
The unofficial apps can let you do just about anything, from changing the GUI (graphical user interface) layout to the actual GUI (eg add the Android pattern lock) to App Store tweaks (eg allow you to download large apps over 4G

You get access to do almost anything. It's sick. I get free apps and music too.

Thats a great way to end up with a keylogger or virus. That will only need to happen one time and you will be wishing for years it never happened.

It is more likely to get a virus, it's not locked up by Apple, can get completely screwed if done wrong. Those are some of the big things.

If you jailbreak an IPhone, police will track you for hacking Apples software.