LiveJournal is an OnlineCommunity which offers people a place to set up an OnlineDiary and get responses from others, etc. The entire site is run from the OpenSource concept and paid accounts give users more features which helps pay for the servers:
Most people pay to support the project rather than for features.
The real crux of LiveJournal is the Friends page, a list of the most recent posts from people one has added to one's Friends list. This turns LiveJournal into a DiaryCollective? of weblogs more writing-oriented than the common news weblog, and peer pressure within existing groups to join driven by MetcalfesLaw. [An explanation of LJ friendship and access policies can be found here.]
The community is probably the most successful OnlineDiary/WebLog service around, having over 900,000 active users of 1.8 million total accounts at the beginning of 2004.
There are several other sites running on the LiveJournal codebase. See also sister site DeadJournal? at http://www.deadjournal.com.