What is Twitter?  How does it work?  Created in 2006, Twitter is a free social networking site that encourages users to send and receive messages, either via the Twitter websites, Short Message Service (SMS) or external applications. “Tweets” are limited to 140 characters, which are displayed on the user’s Twitter profile page, and subsequently delivered to the user’s “followers.”  As a Twitter user, you can either allow open access to your tweets, or you can restrict access to your circle of followers. 

The 140-character message limit was initially set for compatibility with SMS messaging, and has brought to the web the kind of shorthand notation and slang commonly used in SMS messages. It has also spurred the usage of URL shortening services such as tinyurl, bit.ly and tr.im, and content hosting services, such as Twitpic and NotePub to accommodate multimedia content and text longer than 140 characters.

Currently, Twitter is ranked as one of the 50 most popular websites worldwide by Alexa’s web traffic analysis, with an estimated count of 6 million unique monthly visitors and 55 million monthly visits. Twitter has a monthly growth rate of over 1300%, however, once registered, only about 40% of Twitter users regularly use the service.