When a jailbreak tool exploits an iOS vulnerability, it gains "root" access to the filesystem. The tool then executes a script to download and unpack the Cydia binary. It also installs APT, Berkeley DB, and other dependencies required to run the graphical interface. The Cydia icon then appears on the home screen, signifying a successful jailbreak.
: A frontend for APT that enables adding, removing, and updating software from various repositories. cydia installer
One of the most overlooked aspects of the Cydia installer is its seamless payment system. Saurik integrated Amazon Payments and later other providers to allow developers to sell tweaks. This turned jailbreaking from a hobbyist hack into a viable economy, generating millions of dollars for developers who specialized in iOS modification. When a jailbreak tool exploits an iOS vulnerability,