The company's partner program has over 1 million creators in 30 countries earning money from YouTube channels. Thousands of them bring in six figures annually.
It's spawned an ecosystem of what's called "multi-channel networks," like Maker Studios, which Disney bought for $1 billion, or AwesomenessTV, which DreamWorks Animation snapped up for $33 million. These media giants value YouTube's young stars and devoted fan base, which is increasingly hard to reach through traditional advertising.
So what's next?
The challenge for CEO Susan Wojicki, who started in February, is growing viewership and revenue. YouTube has been working to place its app on more TVs and set-top boxes to make it a more enjoyable "lean back" experience, to grow the amount of time people spent watching YouTube from 10 or 15 minutes a day, to match the hours people spend with the TV on.
The more people watch, the more the company can capture part of the $212 billion global TV ad marketplace.
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To get people to watch more, it needs to make sure it remains the destination for all sorts of content, especially the higher quality professional and semi-professional variety.
A number of YouTube's biggest stars are being lured to other platforms to release new content, like Vimeo's on-demand platform, or Maker.TV. They offer higher ad rates and a greater share of ad revenue. But no matter what, YouTube has something they don't: The biggest audience on the market.
—By CNBC's Julia Boorstin