Install Cydia on your iOS device using the Cydia installer available from Pangu8.com. Pangu8.com has multiple versions of the Cydia installer for use with different iOS devices and different device generations. Keep in mind that Cydia only works on jailbroken iOS devices. While installing Cydia on factory-standard iOS devices sometimes works, neither the app nor any of its features are accessible.
Because Cydia only works on jailbroken iOS devices, installing Cydia on a factory-default device requires first using jailbreaking tools such as Pangu or TaiG. Keep in mind that jailbreaking your iOS device always violates the product's warranty. Improperly jailbreaking the device can also lead to a partial or total loss of functionality, colloquially known as "bricking" the device.
Cydia is similar to Apple's proprietary App Store. Unlike the App Store however, Cydia allows users to download and install apps from third-party and unverified developers. Cydia users can also download pirated games and emulators using the application, which can violate copyright in certain situations. Most of the apps available on Cydia are provided free of charge, while others require users to pay a fee.
One of Cydia's unique early features was its ability to allow a user to install an older version of iOS. Normally, Apple forces users who restore their devices to install the newest version of its mobile operating system. However, after iOS 5.0, Apple increased the system's security, limiting the utility of this feature.