One of the ‘silent majority’ in an electronic forum; one
who posts occasionally or not at all but is known to read the group's
postings regularly. This term is not pejorative and indeed is casually
used reflexively: Oh, I'm just lurking.
Often used in
the lurkers, the hypothetical
audience for the group's flamage-emitting regulars.
When a lurker speaks up for the first time, this is called delurking.
The creator of the popular science-fiction TV series Babylon 5 has ties to SF fandom and the hacker culture. In that series, the use of the term ‘lurker’ for a homeless or displaced person is a conscious reference to the jargon term.