Journalist Mathew Ingram first said this and it is true: ‘Twitter is the first draft of history’. Cases in example: The Mumbai Terror attacks, The Colorado Plane crash, The Hudson River Plane crash. In each, people reported about the incidents using their mobile phones and posting to Twitter.

The basics of Twitter are simple.

* 140 characters limit - so, be concise
* Follow - Doing this, you are able to see the tweets of whomever you follow, and anyone following you might see your tweets
* @Replies - the @Replies tab serves as an inbox of public tweets meant for your attention. You can also start a tweet with @[username] and it will end up in that inbox
* RT - Short for retweet. When someone tweets something you like and you want your own followers to see it, you type 'RT' , then paste the tweet (with the @[username] included) and hit update.
* DM - Short for Direct Messages. Basically, emails limited to 140 characters, which you can use for private conversations.

What to post through Twitter:

Useful links you've found; interesting things you have just heard or seen; latest quote about your industry; Re-Tweets about something interesting you 've found on Twitter; what you are doing or will be doing (only if it is interesting); ask a question or seek help; and finally, send a message to someone using the @... code.

Search for people to follow/befriend:

The first thing you must do after joining Twitter is to use the search tool to find the top people in your field of work. Search by name or subject. Jump to names you like and click on 'follow'. This way you know what the top guns in your industry are up to.

Search for activity around a topic: Use Tweetscan to see what people are talking about http://www.tweetscan.com/
Search for most popular links users are sharing: Use Twitturly http://twitturly.com/

Publish news articles from sites onto your Twitter account: Use Twitterfeed http://twitterfeed.com/
Update Twitter from your mobile phone: Read this articles on 20 mobile tools for Twitter

One such tool, but only for American and Canadian users is Jott. http://jott.com/Default.aspx

To post to Twitter from your iPhone, use TwitterFon http://www.naan.net/trac/wiki/TwitterFon
Publish photos on Twitter from your mobile phone: Use Twitpic http://twitpic.com/
Post pics from Flickr: Use Snaptweet http://snaptweet.com/
Post Photos and Videos, both: Use Twixxer http://twixxer.com/

More useful links about using Twitter:
Firefox plugin that does all sorts of Twitter magic:
A more thorough look at various twitter tools and tricks can be found on this article by Paul Broadshaw
A Twitter Tip sheet is here
30 journalists to follow on Twitter A page created by Kevin Sablan
3 ways to follow Twitter journalists without tweeting