Some people use it to connect with people they know, like an on-the-go instant messaging service. When you type in "Headed to Starbucks." all your friends can get the update. The message might prompt a get-together if someone you know is nearby. You can also broadcast your opinion of the movie you and your friends most recently saw, starting up a conversation that might be continued when you're all together face-to-face. If you want to limit your Twitter use to just your friends, you have the option of protecting your tweets. That means that only people you allow can view what you're saying.
But there are reasons why you might want to leave your tweets unprotected, allowing people from all over the world to "follow" you. One of the most immediate advantages to opening your Twitter account to others is that you can ask questions and get them answered in real time. You can ask if anyone has had any experience with a particular product you're considering purchasing, or if they've ever worked with a company you're thinking about using. People with answers to your enquiry will gladly tell you what they think. Twitter has a 'reply' button that will let people tweet directly to you, or they can '@ message' you. That just means that they put @[your user name] in their tweet, so that your attention is flagged (there's a section on your homepage where you can view all the messages that @ message you). An @ message will be visible to the general Twitter population, so others can get in on the conversation.
Twitter also has a search feature that can be used to get others' opinions. For example, you can search "Andrew Bird" and tweets about specific songs, links to articles and YouTube videos, and general opinions will show up. It's a great tool for quick research regarding current views, and you don't have to wait for anyone to respond to your tweet.
If you own a business or website, Twitter can be a great way to drive traffic. Let's say you sell scientific equipment. You've got a small physical location, but most of your business comes from orders over the Internet. You can focus your tweets on science-related information, so that you know that the people who follow you have an interest in science. You might talk about the latest scientific news, cool experiment ideas, or post links to articles online. This is the kind of useful information that will keep your followers interested in what you're saying. Once you have their interest, you can-every once in a while-send out a tweet about a great sale you're having, or a new product you just got in, and link to your website. Your followers get a great deal, and you get more sales.
This showcases some of Twitter's uses. Get on, sign up for an account, and see what else Twitter can do for you!
Ampersand can be found on Twitter as investMT, and would love to connect.