Twitter is a social network. Based on the concept of micro-blogging, you are limited to a certain number of symbols to communicate your message. One thing is certain, Twitter has challenged everyone to be more concise in your message. So what is Twitter? If you are new to the understanding of this third pillar of the three major social networks, which also include Facebook and LinkedIn, you'll enjoy these Twitter facts:

1. Twitter was founded in 2006 by Jack Dorsey, Biz Stone, and Evan Williams.

2. Twitter is a free tool that allows people to send messages back and forth to each other.

3. Twitter messages are text-based and are limited to 140 characters.

4. Twitter is a free service.

5. As of June 2009, there was an estimated 45 million user accounts.

6. Your Twitter bio is restricted to 160 characters.

7. It is used by celebrities, authors, politicians, business owners and other well-known figures.

8. A retweet of a message that you received, can easily be sent to your followers by preceding it with the two letters RT.

9. You can create as many Twitter accounts as you wish.

10. You can add a photograph and customize the design of your main Twitter page.