Happy Birthday, Twitter! The wildly popular micro-blogging platform turns six today.

On its sixth birthday, the site now boasts more than 140 million active users, Twitter announced on its blog Wednesday. Users now send 340 million tweets a day, which is more than 1 billion every three days.

Six years ago, on March 21, 2006, Twitter founder Jack Dorsey posted the very first public tweet on the micro-blogging platform.

"Just setting up my twttr," he wrote. Back then, Twitter was not much more than a vision Dorsey had sketched on a piece of lined notebook paper (left). In the years since, Twitter has skyrocketed to the giant of the social media world.

"Without you, of course, there wouldn't be a Twitter," the blog post reads. "We mark our sixth birthday with you in mind, and celebrate your myriad ways of engaging, enjoying, and emoting on our platform."

Twitter said back in September announced that it had reached 100 million active users. At that time, Twitter users included 75 percent of the NBA's players, 50 percent of the NFL, 82 percent of the U.S. House and 85 percent of the Senate, 87 percent of the Billboard Top 100 Musicians, and 93 percent of the top Food Network chefs. (Who should you follow? Check out our attached slideshow of our top 100 picks.)

In January, Twitter CEO Dick Costolo said the company is planning to be around for many years to come, but has no immediate plans to go public.

"We are going to be really patient about the way we build the business," he said. "We are trying to build a decades-long, lasting business."