IRC

From Wikpedia -
 * Internet Relay Chat (IRC) is a protocol for real-time Internet text messaging (chat) or synchronous conferencing. It is mainly designed for group communication in discussion forums, called channels, but also allows one-to-one communication via private message as well as chat and data transfer, including file sharing.

For a more entertaining version, here's an excerpt from Encyclopedia Dramatica -
 * Internet Relay Chat (IRC) (AKA Multiplayer Notepad) has been around for 65 billion years. It's the bastard offspring of UNIX talk and ntalk protocols.

To put it simply, IRC is like a normal chat system, except instead of chat (which doesn't happen as everyone is either idle or a bot the fbi), the main activity of IRC is op-wars and denial of service attacks. Ops are people who kick and ban those from a room who suck up the least (the non-ops don't have that so they denial of service attack them instead), which causes the banned users to retaliate by DDoSing the ops and the IRC network and ChanServ, then gaining ops on a split.

Unsurprisingly, the existence of channels (to make communication a bit easier) created potential for vast amounts of drama, which quickly transformed from being potential to actual drama, human beings being what they are. Channel and network drama happens at an exponential rate of growth, but since anything rarely goes past words in the IRC protocol, it's entirely harmless and pointless. Stupid drama. IRC also is used to transfer two very different types of important communication.

IRC users are on a continuous quest to gain more status. There are always more channels and more servers on which to gain ops. IRC is also a center for warez. Once you've got lots of ops, IRC users can try and climb the "LeetLadder". You've never seen anything so useless as someone with lots of IRCops who tries to use that status IRL.

Most people use smileys to express their feelings on IRC. Meanings of smileys differ from channel to channel. For example, people on one channel might say "::D" when they see something funny, but on another they might say "=DDDd" to express the same feeling. Acronyms like LOL, ROFL or LMAO are also used to express feelings but, as with smileys, their emotional content differ greatly from channel to channel.

Much lulz on IRC can be had at the expense of nubs, who are often told to scroll up after pasting old memes.