At the heart of Cydia's functionality are repositories, or "repos." These are servers that host packages (apps, tweaks, etc.) which can be downloaded and installed on an iOS device. Cydia comes with a set of default repositories, but users can add third-party repos to access a broader range of software. This open approach has fostered a community of developers and users who contribute to and benefit from the vast ecosystem of customizations and applications. Sileo is a more recent entrant in the scene, developed by a team led by William "S1ri" Vincent and Cody "CydiaSubo" Kaschalk, known for their work on Cydia. Sileo was conceived as a modern alternative to Cydia, aiming to offer a more streamlined and user-friendly experience. It supports all the features that Cydia does, including the use of repositories, but focuses on performance and a more intuitive interface.