THE SIMPLEST way to think of Twitter is as a broadcast text messaging service that allows you to send the same 140 character message to multiple people at once. You create a free account at Twitter.com and you can then start updating by simply answering the question "what are you doing?" Your updates will be seen by people who choose to follow you. In turn you will see the updates of people you choose to follow - similar to "friends" on social networks like Facebook.

To get you started Twitter can pull in your contacts from Gmail, Yahoo Mail or AOL and tell you whether those people are already Tweeting (ie using the service). You can send email invites to those who aren't and Twitter suggests some of its most popular "celebrity" users such as Al Gore, Lance Armstrong and Britney Spears who are fun to follow for a while. Another way to find people to follow is to search for topics you are interested in to see who is talking about them.

Many users simply sit back and look at what's been said but as with any social tool you get more out of it when you participate. Replies, or public postings for the attention of a particular user, can be sent by putting @ in front of the username eg @IrishTimesBiz but you can also send private direct messages.

Although Twitter is thought of as a website serious users turn to dedicated software such as Tweetdeck or Twhirl, which have greater functionality than the site and now account for over 70 per cent of Twitter usage.

- John Collins manages Irish Times Business on Twitter (@IrishTimesBiz)