Cydia is the infamous software application part of iOS, Apple's operating system found on the popular iPhone and iPod Touch, that allows the user to search and download applications specifically designed for a jailbroken iPhone. How does this relate to our class? It is an application (commonly found item in the technology world) that is being used for hacking, or unorthodox, purposes.
What does it mean for an iPhone to be "jailbroken?" To jailbreak an iPhone simply means to allow the device to gain full access (root access) to all features of the operating system. In other words, you are removing all limitations set by Apple when you jailbreak the iPhone.
Jay Freeman, known as saurik in the technology community, developed Cydia in March of 2008. This started as an alternative to the Installer.app on iOS 1.1.
As of August 2009, Freeman estimated that "10% of the 40 million iPhone and iPod Touch owners" have installed the Cydia application.
Cydia's App Store
Saurik introduced, in March 2009, a simple way for application developers to sell their works via Cydia in a unified manner, much like the official App Store. Amazon and PayPal are two ways for developers to accept payments for their works.
Many iPhone users who have jailbroken their devices have found ways around paying for official applications as well as Cydia applications. After installing Installous, one can add "Repos" in order to gain sources for cracked applications from the official App Store. Also, users can downloaded cracked .deb files and "drag and drop" them to their device via iPhone Explorer or similar programs in order to gain free access to Cydia apps as well.