Jailbreaking your Apple devices, like an iPhone or an iPad, allows free downloads of paid apps, free face time chats, cool home lock screens, etc. Personally, I have tried jailbreaking my iPod before… and failed. I nearly bricked my iPod and crashed my computer that time, so I never dared to try again. My friend somehow successfully jailbroke her iPod, but the device became very slow. There are many advantages and disadvantages for jailbreaking your device. Nevertheless, it all depends on how much risk you are willing to take.
Here is a website that thoroughly covers all the fun and trouble for jailbreaking: http://www.risedream.com/blog/2011/09/03/advantages-and-disadvantages-of-iphone-jailbreak/
The How-to guide to jaailbreak:
1. Download greenpois0n RC5.
2. Update or restore your device to 4.2.1. This can be done through iTunes.
3. Launch greenpois0n and select jailbreak.
4. Put device into DFU mode. (Press both home and sleep button down for 10 seconds)
5. Coffee Break! Greenpois0n will do the rest of the job. The device will automatically reboot.
6. There will be a new app icon called the loader. Launch it.
7. Install Cydia for all the fun!
CONGRATS!
Always remember if something goes wrong during jailbreak, it is better to untie the knot before it gets into a tangle.