"Twitter is a service for friends, family, and co–workers to communicate and stay connected through the exchange of quick, frequent answers to one simple question: What are you doing?" -- Twitter official website.
Twitter is a microblogging social media network, available on the Internet and through mobile devices such as cell phones, and BlackBerries. Its two most notable features is its portability and a 140 character limit per post. Created by Biz Stone
Practical Description Twitter is a way to stay up-to-date with all the news that matters to you personally, regardless if the news comes from a newspaper or a childhood friend who now lives in another country. The media spotlight landed on Twitter back in January, where a U.S. Airways plane was forced to ditch into in the Hudson River and the news -- with pictures -- first broke on Twitter. (Miraculously, there were no casualties.)
One of the key features of Twitter from a practical standpoint is that it can be used from mobile devices, which is when it is truly powerful. This is a key attribute often overlooked when trying to understand Twitter and it's 140 character limitation.
Twitter and Traditional Media
In 2009, traditional media such as television began to notice Twitter. When U.S. Airways flight 1549 was forced to ditch into the Hudson River, a number of people used Twitter to spread the news, some as they witnessed it. Pictures taken were posted to sharing sites and links to these pictures were spread through Twitter, which were then picked up by various media and used to cover the story.
Criticism and Misuse
Most of Twitter's criticism stems from the misuse of the service. Tweets describing breakfast and various surface thoughts create the image of a novelty with little practical use. Many people are still unsure of how to use the service or its purpose, and combined with a great deal of media attention it appears to be "Much ado about nothing".