The concept of presence has had a good run
as a key dynamic of synchronous and semi-synchronous online
communications. UNIX systems have their who and
w commands that allow you to see who is logged into the
system and what they are currently doing, complementing the
say command to write messages to your colleague’s terminal.
In the days of IRC, if you weren’t logged in, you wouldn’t receive
messages; long-running terminal sessions aided by the likes of screen were necessary in
order to get messages while away, and users would change their nicknames
to ‘ann1e|afk’ to indicate they were ‘away from keyboard’ (some servers
also allowed an ‘away’ flag that caused some clients to grey out the
absent user’s name).
XMPP, a standardized protocol for instance messaging that was once used by Google and Facebook in addition to a number of smaller providers, enshrined the importance of presence in its name: eXtensible Messaging and Presence Protocol. Presence was also important in earlier proprietary instance messaging protocols such as AIM and MSN Messenger; Skype still supports the standard set of presence indicators: online, busy, do not disturb, away, and free for chat.
[XMPP]: eXtensible Messaging and Presence Protocol {:.acro} [UNIX]: UNIX {:.acro} [IRC]: Internet Relay Chat {:.acro} [AIM]: AOL Instant Messenger {:.acro} *[MSN]: Microsoft Network {:.acro}