Presence leveraging refers to any technology that supports and expands presence, the ability of a network subscriber to locate and identify any other user's computing device as soon as the other user connects to the network. Presence technology can be difficult to coordinate among servers and individual end users with divergent operating systems in large networks.
Presence leveraging is an integral feature of SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE), an add-on to the Session Initiation Protocol (SIP). Presence leveraging is also a feature of Extensible Messaging and Presence Protocol (XMPP), which is based on the Extensible Markup Language (XML). Both SIMPLE and XMPP are commonly used to support real-time communications (RTC) in instant messaging (IM) applications.
The ultimate objective of presence leveraging is to facilitate immediate, real-time, two-way communication among all users of the Internet who do not object to being located or identified, regardless of operating platform. Of course, certain users may not want to be located or identified at all times. It is to be expected, therefore, that presence-blocking software will evolve along a parallel track with presence leveraging technology.