100 million active users

Twitter was founded about five years ago. Today, the company announced that they reached their 100 millionth ‘active’ user.Each month the service has 400 million unique visitors. Astonishingly, the micro-blogging service posts about a 350 billion tweets per day--says the company.

Of these active users about half access the social, micro-blogging service on their mobile phones.

There are questions to be asked of Twitter's latest round of stats announcements. One big question is how many of their daily sign-ups are spam accounts? Also, how many accounts are unique owners? Still the latest Twitter numbers are quite impressive.

Source:
https://blog.twitter.com/2011/09/one-hundred-million-voices.html
https://twitter.com/#!/twitter/status/91890490089275392