10 Top Twitter Users From Barack to Bieber

8. YouTube
Twitter handle: @youtube
Joined Twitter: Nov. 13, 2007
Followers: 19,063,039
First tweet: August 28, 2008. "Follow Obama's nomination week at http://www.youtube.com/user/2008conventions"

Google's video service is the only brand in Twitter's Top 10, but that's not really surprising on a site so focused on mobile users. All of that video content reaches roughly 56% of the U.S. Internet audience, according to ComScore. That rivals Facebook's reach and outpaces heavy hitters such as Wikipedia, Amazon and AOL .

Also, take a look at that first tweet. In four years, YouTube has become a hub for U.S. political coverage as well as the site your great aunt uses to watch her cute cat videos. When you become as important to protestors in embattled countries as you are to office workers just getting around to watching Gangam Style, that's about as close to indispensable as you can get.

7. Taylor Swift
Twitter handle: @taylorswift13
Joined Twitter: Dec. 6, 2008
Followers: 20,399,623
First tweet: Dec. 6, 2008. "apologizing to a very needy cat for being gone so long."

If only that poor cat knew what was to come. Swift's time on Twitter has been like a personal timeline. She's sold close to 16 million records in that span, had seven Top 10 singles, won six Grammy Awards and one particularly memorable MTV Video Music Award that introduced "I'ma let you finish" into the American lexicon.