Twitter

Twitter is a very simple service that is rapidly becoming one of the most talked about social networking service providers. When you have a Twitter account, you can use the service to post and receive messages to a network of contacts, as opposed to send bulk email messages. You can build your network of contacts, and invite others to receive your Tweets, and can follow other members posts. Twitter makes it easy to opt into or out of networks. Additionally, you can choose to stop following a specific persons feed.