WebRTC promises to greatly simplify the development of multimedia realtime communications, without the need to install an application or browser plug-in. It enables this by exposing a media engine and the network stack through a set of specialised APIs. Application developers can use these APIs to easily add realtime communication to web applications. The defined use cases that have been identified in the early stages of the standardisation have a wide range of applicability. Many of the initial applications focus on communications between applications running on web browsers, but it is expected that WebRTC will also allow for interoperability with several existing communications protocols. For that and other reasons, the signalling interfaces have been determined to be out of scope, thus allowing the service providers to choose the best suited protocol or signalling mechanism for their users.