At 4:50 p.m. on March 21, 2006, Jack Dorsey wrote "just setting up my twttr." Five years later, Dorsey and his fellow Twitter co-founders Biz Stone and Evan Williams have transformed a neat idea conceived during a daylong brainstorming session into a worldwide phenomenon. Twitter is now valued at more than $10 billion and has gone from zero to 1 billion tweets per week.
But not all tweets are created equal. Here's a countdown of five historic moments, brought to you by Twitter.
5. Twitter and Space
TV broadcasts of astronauts are so 1969. On January 22, 2010, Flight Engineer T.J. Creamer broadcast the first tweet from outer space: "Hello Twitterverse! We r now LIVE tweeting from the International Space Station -- the 1st live tweet from Space! :) More soon, send your ?s"
The message was made possible by a NASA software upgrade that gave Space Station astronauts direct personal access to the Web. Previously, tweets from astronauts had to be e-mailed down to Earth, then later posted to Twitter by ground-based workers.
4. Twitter and Obama
President Barack Obama wasn't the first politician to use Web 2.0 technology on the campaign trail, but he was the first to truly harness the viral powers of Twitter and other social networks to raise funds and keep his followers up to date on his progress.
When Obama won the presidency, he tweeted: "We just made history. All of this happened because you gave your time, talent and passion. All of this happened because of you. Thanks." Could Obama have made history without Twitter? Maybe -- but the microblogging service certainly helped.
3. Twitter and Iran
Even after the Iranian government shut down Twitter's Web site and halted access to SMS services, Twitter found a way through and kept the world up to date on the violent protests surrounding a contentious election.
Twitter was also credited with driving coverage of the event on major American TV news organizations, bringing important news to the United States that may not otherwise have received as much attention as the event deserved.
Twitter even delayed its scheduled downtime for site maintenance to keep information from Iran flowing, acknowledging in a blog post that Twitter was playing the role of "an important communication tool in Iran."
2. Twitter and Japan
Not only are many families and their loved ones using Twitter to keep in touch after the devastating 8.9 magnitude earthquake and tsunami in Japan in March, organizations and relief efforts are also taking to Twitter to post information about everything from emergency phone lines for non-Japanese speakers to tsunami alerts, altered train schedules, and lists of shelters for those left homeless.
An hour after the quake hit Japan Twitter experienced 1,200 posted tweets per minute and, at its height, was nine of Twitter's top 10 Trending Tropics.
1. Twitter and Egypt
After 18 days of tumultuous protests -- many fueled or managed via Twitter -- Egyptian President Hosni Mubarak gave up his seat of power and handed authority over to the nation's military leaders. Even after 88 percent of the country's online networks were blocked by the government, protesters used Twitter and other social media tools to fuel their determination.
When Mubarak finally stepped down, President Obama noted the role of technology in the uprising, praising Egyptians who used "their creativity, talent and technology to call for a government that represented their hopes and not their fears."
Without the communication enabled via Twitter, the political upheaval may not have been as successful or quick. In this case, Twitter deserves a lot of credit as the means of organizing the passions of a citizenry behind a cause, connecting people all over the world, and affecting world events. Not bad for a 5-year-old.