Twitter (commonly known as Twitter in unofficial Chinese) is an American social networking and micro-blogging service, and is one of the ten most visited websites on the Internet worldwide. It is a typical application of micro-blogging. It allows users to update messages of up to 140 characters, which are also known as "tweets". The service was founded by Jack Dorsey in March 2006 and launched in July of that year, Twitter has become so popular around the world that, as of March 2012, Twitter had 140 million active users, according to current Twitter CEO Dick Costello, and Twitter has been described as "the messaging service of the Internet. Twitter has been described as "the messaging service of the Internet".