Cydia. How To Install Cydia On iPhone, iPad, iPod Touch
Cydia is a third-party, independent installer application for iPhone, iPad and iPod touch. Cydia is developed by Jay Freeman (Saurik) and it’s actually much similar to Apple’s app store. Cydia allows you to download tons of tweaks & utilities that you’ll need to make the best out of your iOS device. Cydia brings you many applications that can be downloaded either for free or for a small amount of money.