History of MMOs

An MMO (Massive Multiplayer Online games) is a game that is capable of supporting 1000s of players at the same time and contains at least one virtual world that remains active when the user leaves. The current largest western MMO is World of Warcraft with 11 million subscribers. China's "Happy Farm" has it beat with 228 million subscribers and an average of 23 million users logged in every day. 

This awesome chart depicts most of the history of massive online gaming. I actually started playing MMOs with a game called Neverwinter Nights (seen in the picture above) which debuted in 1991. This chart has the added effect of making one feel really old.