Founded in 2006 by Jack Dorsey, Noah Glass, Biz Stone and Evan Williams, Twitter is an online social networking and microblogging service that enables users to send and read 140-character messages called tweets. The service gained worldwide popularity, reaching 500 million registered users in 2012.
In 2012, Twitter partnered with Yandex, a Russian search engine, and acquired video company, Vine, which launched in January 2013. Twitter released Vine as an app allowing users to create and share six-second looping videos.
In 2013, Twitter acquired Trendrr and MoPub. Twitter made an initial public offering in November 2013, opening shares at $26 and closing at $44.90, giving the company a valuation around $31 billion.