Twitter Now

Twitter is a free social networking and micro blogging service that enables its users to send and read other users' updates known as tweets. Tweets are text-based posts of up to 140 characters in length which are displayed on the user's profile page and delivered to other users who have subscribed to them (known as followers). Senders can restrict delivery to those in their circle of friends or, by default, allow anybody to access them. Users can send and receive tweets via the Twitter website threw short SMS messages. The service is free to use over the Internet, but using SMS may incur phone service provider fees.

Since its creation in 2006 by Jack Dorsey, Twitter has gained extensive notability and popularity worldwide. It is often described as the "SMS of Internet," in that the site provides the functionality for other desktop and web-based applications to send and receive short text messages, often obscuring the Twitter service itself.

Estimates of the number of daily users vary as the company does not release the number of active accounts. In November 2008, Jeremiah Owyang estimated that Twitter had 4-5 million users. Twitter as the third most used social network. Facebook is the largest followed by Myspace.

Some NASA projects such as Space Shuttle missions and the International Space Station provide updates via Twitter. During the 2008 Presidential campaign, The Democratic Nominee Barack Obama used Twitter as publicity mechanism. The Nader–Gonzalez campaign updated its ballot access teams in real-time with Twitter and Google Maps.

There are many services and applications that work with or enhance Twitter. Many are designed to allow easy access to Twitter from specific devices, such as the iPhone or BlackBerry whilst others are designed to make it easier for users to access and update their Twitter account.