What is the twitter software? and how is it different from normal instant messengers?

What is the twitter software? and how is it different from normal instant messengers?What is the twitter software? and how is it different from normal instant messengers?
From Wikipedia:

"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, Short Message Service (SMS) or applications such as Tweetie, Twitterrific, Twitterfon, TweetDeck and feedalizr. The service is free to use over the Internet, but using SMS may incur phone service provider fees.



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