The core library defines capabilities: features common to various websites. Forexample, http://www.youtube.com and http://www.dailymotion.com are both videosproviders: Weboob defines the “ICapVideo” capability.Each backend interfaces a website and implements one or many of thesecapabilities. Backends can be configured, which means that the end-user canprovide personal information to access the underlaying website (login/passwordfor example).Applications offer the ability to the end-user to work with many backends inparallel, in a multi-threaded way. For example, one could search a video onmany providers websites. Applications are toolkit-agnostic. They can use Gtk,Qt or text-only, more adapted to reuse data through pipes.The core library provides base classes which help the developer to writebackends and applications.