Thanks to Mike Calimbas for granting permission to use content from his post "Twitter Guide for Newbies"

What is Twitter?

Twitter is a microblogging community. In other words, imagine sending out a text message to 2 people. Or 200 people. or 2,000 people. Now imagine being able to follow the text messages of the same amount of people as well. All these people interact with one another in a real-time environment. You get to see everything that is happening in the world first-hand, free of the bias and filtering of traditional channels.

Why use Twitter?

Some use twitter simply to see what is going on in the world in real-time. Whether it’s with global news, activities within companies or industries, or in their own personal and business networks. Others use it as a means of mass-communication, as it enables them to communicate to a broad spectrum of people rather than going about the tedious task of relaying the same message individually. Even more use Twitter for branding purposes, whether it is to push their companies or personal agenda. Other uses include marketing, reputation-management, or simply personal use with the doctrine of continuously telling the world how you feel, 140 characters at a time.

Significant News Events on Twitter

• Student ‘twitters’ his way out of Egyptian Jail. (link) - A journalist sends out a 2-word twitter message, “in jail”, right before his arrest. The message spreads virally through the network until it reaches someone who can get him out.
• Newark Airline crash survivor twitters “Holy Fucking Shit I Was Just In A Plane Crash!” to break the news that Continental airlines 737 had slid off the runway in Denver.
• Following the Pirate Bay Copyright Trial on Twitter with real-time accounts from inside the courtroom through the Pirate Bay Founders & defendants. #spectrial on twitter.com
• How Twitter Warned of a Death Threat
• Putting Twitter's World to Use via the New York Times.
  

Learn more by Searching Twitter

Twitter as Searchable Thought Stream
Tips on How to Search Twitter



Evan Williams presentation on Unexpected Uses of Twitter at TED.




Common Craft explanation... seek audio addition from Lee LeFever





More to learn?
'Butterscotch' Twitter Tutorials for Beginners


Why is the Fail Whale Smiling?: Sample Tweets To Demonstrate the Variety of Ways of using Twitter