Twitter celebrated it 6th Birthday on March 21, 2012. To mark the occasion, the company in an official blog post revealed that there are more than 140 million active users on Twitter who together send as many as 340 Million Tweets a day. This amounts to more than a billion Tweets every 3 days.
This is what the company had to say on the occasion: "When @jack first sketched out his notion in March 2006, no one could have predicted the trajectory of this new communication tool. Now it seems that there are as many ways to express yourself in 140 characters as there are people doing it"