I keep hearing about Twitter, what is it and how can I use it?

We wrote about Twitter once before after a few clients mentioned it and we could not entirely see the point. However, Twitter are publishing a handbook which they claim will explain:

• What Twitter is all about
• Why people tweet
• FAQs about Twitter & the Twitterverse Glossary
• How best to communicate with people on Twitter
• How to find and reply to those @ messages sent directly to you
• How people are making money by using Twitter
• Where to download the most popular resources to use with Twitter
• The dangers and the future of Twitter and the Twitterverse