Tweet Tweet: Robin Roberts Joins Twitter

March 21, 2011— -- Robin Roberts has entered the "Twittersphere."

Five years after the micro-blogging site Twitter introduced the world to the "tweet," Roberts sent her first 140 character message by tweeting, "I'm finally here! Joining Twitter in honor of you. My way of saying thanks for all your love and support for @GMA."

Follow Robin on Twitter here.

The micro-blogging company launched five years ago on March 21, 2006. The first tweet by company co-founder Jack Dorsey, was simple "inviting coworkers".

Despite Twitter's 140-character maximum per tweet, the service has had an enormous impact on the way people share information.

Since its launch, Twitter has directly influenced change around the world, facilitating the fall of governments and creating a powerful platform for social and political activism.

Unrest in the Middle East – most recently in Libya and Egypt, but going back to 2009 in Iran -- were heavily influenced by the ease with which Twitter allowed participants to share critical information that governments would have suppressed.

It's also allowed many people to have a new voice, and some celebrities – including Charlie Sheen and Gilbert Gottfried – have tweeted their way straight to infamy.

Twitter also has allowed many public figures to bypass traditional media to get their message out directly to followers.On its website the company says it has 175 million registered users, with 370,000 people signing up every day. An estimated 140 million tweets are sent each day, the company said on its blog this month.

The company was founded by Dorsey, Biz Stone and Evan Williams.

In January 2008, Twitter had eight employees. The company now employs 400 people.

Step 1: Go to Twitter.com and sign up for an account. It's free.

Step 2: Pick a username. You can do a nickname or a variation of your name.

Step 3: Figure out who you want to follow. You can do a search for celebrities you're interested in getting tweets from, or athletes or politicians, or anyone else who interests you.