Jailbreaking

• An iPhone must be jailbroken before you can install Cydia. To do this, visit a website like Jailbreakme.com. Jailbreaking installs a small software program that overrides restrictions within the iPhone’s iOS operating system. Note that Apple views jailbreaking as a violation of the iPhone end-user license agreement which can void your warranty and disrupt performance. Read the instructions carefully before installing any jailbreaking software. You should also research the software to ensure there are no security risks, such as viruses, associated with the software. You can remove the jailbreak by connecting the iPhone to iTunes and restoring the iOS or by upgrading your iOS to a new version.
  
  

Installing and Using Cydia

• After jailbreaking your iPhone, a new icon appears on the iPhone display. Tap this icon, then tap on the Cydia icon. This installs the Cydia application to the iPhone. When the installation is finished, tap the Cydia icon to open the app and browse the Cydia app library. Unlike the Apple App Store, Cydia does not host the apps itself. It is a directory of apps hosted by different app developers.
  
  

Apps

• Cydia lists thousands of apps that are not available from the Apple App Store. Many have been rejected by Apple because they violate Apple’s terms of service. Many developers simply prefer to make their apps available through Cydia, rather than through Apple. Most apps listed by Cydia are free to download. Other apps can be priced anywhere between $0.99 and $20. You can browse a sample of applications available at cydia.saurik.com using a Web browser, then clicking the "Cydia Store" button, or the "Featured" button.
  
  

Upgrades

• Because Cydia and its related applications require a jailbroken iPhone, you will lose access to them when you upgrade your iPhone iOS. Upgrading or restoring an iPhone removes any jalibreaking software from the device. You must jailbreak the iPhone again, then reinstall Cydia, then reinstall the apps. Cydia does keep records of the apps you have downloaded so you can download them again. Check to see if your jailbreaking software, Cydia and your downloaded apps will be compatible with the new iOS before upgrading your iPhone.