Nearly the whole world is following this company. Twitter operates a free digital service site that blends social networking with the ability to post short messages (or micro-blogs) limited to 140 characters or less, commonly known by users as "Tweets." Twitter's service works equally well on personal computers, mobile devices, and smartphones. The service has become a key communication platform as major events unfold live in real-time around the world. Currently Twitter claims more than 300 million users worldwide. Founded in 2006, Twitter went public in 2013, raising about $1.82 billion in the process.