Something remarkable happened on the Web during the last few years. Initially the Web was like a spectator sport where millions of us sat around the stadium and watched the creation of a small number of people. That picture started changing a few years ago when a large number of us got off our seats and walked into the playing field. We were not passive spectators any more, and quickly realized while it is enjoyable to watch the game, it is lot more fun to play it too. Today many of us actively change the Web almost every day by writing blogs, commenting on them, exchanging notes through Facebook and Twitter, posting our photographs and videos, writing product reviews, or simply by voting on something. What was strictly a read-only medium became a read-write medium. What was a passive activity became an active one. The growth of Web 2.0 has been phenomenal and spectacular.
During all this time the number of people on the web has been growing steadily. According to internetworldstats.com, the number of web users across the world is 1.7 billion in 2010, and Facebook, by far the most popular social media site, have nearly 500 million users. Therefore, the percentage of web users who are on Facebook is about 29%. The web metrics company Alexa also estimates that 34% of all web users are on Facebook. This is a jaw-dropping number, and far exceeds any other social media site, including Twitter, which enjoys less than 7% of all Web users (see Alexa graph).
