Twitter Reaches 2 Billion TweetsTwitter Reaches 2 Billion Tweets

Twitter reached 2 billion tweets in May, a milestone that marks a doubling of the number of short messages posted on the micro-blogging site in five months.

Pingdom, which provides an uptime monitoring service for Web sites, posted on Tuesday a graph that shows a steady increase in the number of tweets staring in December 2009, when the site hit the 1 billion mark. To be precise, the number of tweets in May reached 1.99 billion, but Pingdom said the number was "close enough" to call it 2 billion.

Pingdom gathered a number of other statistics about the popular Twitter for the month of May. A total of 64 million tweets were sent each day, or 2.7 million per hour, 44,481 per minute and $741 per second.

Pingdom had predicted that Twitter would reach almost 6 billion tweets per month by the end of the year. However, the company acknowledged on Tuesday that the site might not reach that number this year.

Nevertheless, Twitter is growing at a healthy pace.

"Close to doubling the volume of monthly tweets in the last six months is no small feat," Pingdom said on the company's blog.

The numbers cited by Pingdom represent all tweets that pass through Twitter, including those from the site's application programming interfaces. Third-party sites and applications use APIs to connect to the Twitter platform. Tweets are the messages broadcast through Twitter to social networks built by users. The messages have a 140-character limit.

Pingdom monitors Twitter usage, but not the number of users. Web metrics firm ComScore, which monitors the latter, found that four out of five Internet users in 2009 visited social networking sites on a monthly basis. Twitter and Facebook propelled much of the growth in the category, according to ComScore.