About Twitter.com

Twitter is an online social networking and “microblogging” service that enables users to send and read short 140-character text messages, known as tweets. Their mission is:

Twitter helps you create and share ideas and information instantly, without barriers.

Registered users can read and post tweets, but unregistered users can only read them. Users access Twitter through the website interface, SMS, or mobile device app.

Twitter was created in March 2006 by Jack Dorsey, Evan Williams, Biz Stone and Noah Glass and by July 2006, the site was launched. The service rapidly gained worldwide popularity, with 500 million registered users in 2012, who posted 340 million tweets per day.

What’s in a Tweet?

Inside a Tweet you’ll see photos and videos from people you know or behind-the-scenes moments from the biggest stars. You can link to news stories, blogs, websites and apps.

@username

Your @username is your unique identity on Twitter. People will use your @username to mention you in Tweets and to send you messages.

#hashtag

A hashtag is any word or phrase with the # symbol immediately in front of it. This symbol turns the word into a link that makes it easier to find and follow a conversation about that topic.

Retweet

You can pass along someone’s Tweet by clicking the retweet icon. Retweeting is a lot like forwarding an email — you’ll send along someone else’s Tweet to all of your followers.

— information from Wikipedia and Twitter