A spanning tree of servers which clients connect to. At some point specified as RFC 1459 RFC 2812, modern-ish summary is recommended.
refer to RFCs or summary for commands and args,
of note: PRIVMSG is also used for channel messages,
not just user-user.
1[:prefix] command params...<CRLF>
in descending level of privileges:
1~ founder
2& protected
3@ operator
4% halfop
5+ voice