A system and a method for establishing or specifying the online status of a user
forming part of an instant messaging system. The IM system includes clients having
IM client applications, an IM server, and a user information database that is selectively
connected to the clients via the internet. The user database stores an activity
status for each user's activity with the IM server system. The activity status
includes: (i) a time variable signifying the time of or time since the last prescribed
involvement with the IM server; and (ii) a probability variable signifying the
likelihood of the user still being online. Monitoring means is provided to continuously
monitor user activity with said IM server and to continuously update the activity
status of users stored on the database. Checking means is also provided to check
the activity status of each user stored on the database and adjust said probability variable.
