The University has one principle catalogue, iDiscover which is the discovery tool that is part of out library management system (LMS). This is available to all users of the University. A few college manage their own LMS and these will come with a different catalogue.
iDiscover: this is the library's catalogue with a Google-like interface. It reflects the current holdings of all Cambridge libraries, including ebooks and some other digital collections. iDiscover is good for initial searches and faceted searching of the catalogue.
College catalogues: these operate independently and reflect the holdings of the specific college. They are good for up-to-date information on the loan status of material, the option to recall items and accessing your library account. To check if your library has its own catalogue, visit the library section of your college website. Non-members of such colleges will probably be able to search these catalogue but some system functionality may not be available to you.