Simply put, a Tweet is a message sent on Twitter. To send or receive a Tweet, you have to create a free account with Twitter. You also need to have friends and contacts with Twitter accounts -- otherwise you're typing to the void. Of course, you could use Twitter as a blog and keep all of your Tweets public, meaning anyone could read them on your personal Twitter profile page. But if you want to use Twitter as a way to keep in touch with friends, you'll need to convince them to sign up, too.
Once you have an account, you can begin building your network of contacts. You can invite other users to receive your Tweets, and you can follow other members' posts. As you receive Tweets, you may discover you're looking into only part of a conversation. You'll see your contact's posts, but if he or she is sending messages in response to someone who isn't in your network, you won't see the other person's messages.
Tweets have a few limitations, mostly due to the fact that Twitter's design relies heavily on cell phone text messages. Tweets can only have up to 140 characters before the system cuts off the rest of the message for cell phone users. Members can read full Tweets on their Twitter Web pages or by using a third-party developer's desktop or Web-based application.
In the beginning, Tweets were text only. Now, Tweets can include pictures, as well as six-second video clips (courtesy of Vine, which Twitter purchased in 2012).
Twitter makes it easy to opt into or out of networks. If you join Twitter and find that you're being bombarded by Tweets from a particular member, you can choose to stop following his or her feed.
You don't have to generate original content in order to send Tweets. You can simply share the Tweets that other people create, in effect forwarding their message all of your followers. This is calling Retweeting.
As a way of categorizing and grouping messages, many users use the hash symbol followed by the Tweet's subject. For example, if you're Tweeting about your new car, you might include #newcar #porsche #bankaccountempty as part of your message. These hashtags make your message more searchable for other users.
In the next section, we'll learn about Twitter's many applications.