Presence

Presence or presence information, conveys the ability and willingness of a user to communicate with other users on a network, across a set of devices. IETF RFC 2778 defines a model and terminology for describing systems that provide presence information. In that model, a presence service is a system that accepts, stores, and distributes presence information to interested parties.

a.k.a.

Presence Information

RFC 2778, A Model for Presence and Instant Messaging