Streaming video site Twitch said Monday that more than 21 million people tuned in to watch its coverage of this month's major video game convention, the Electronic Entertainment Expo -- better known as E3. That's compared to about 12 million viewers in 2014 and 9.5 million the year before.

The site streamed all of the major press conferences and its own content, as well as hosting programming from its diverse community of self-streamers. According to an infographic released by Twitch, as many as 840,000 people were watching video streams at the same time -- 16 times the number of actual show attendees. Overall, the company said, viewers consumed just under 12 million hours of video from the four-day show.


(Courtesy of Twitch)

As for the companies that were at E3, Twitch offered few specific details  about how they fared. But it did say that Microsoft's news conference rated the highest of any hardware maker. Electronic Arts, meanwhile, took the crown for the software makers' conferences.

The success of Twitch, which Amazon bought for roughly $1 billion last year, has shown how quickly the social video space has taken off in the world of video games. According to a study last year by the Wall Street Journal, Twitch is the fourth largest driver of peak Internet traffic in the U.S., ahead of Hulu. (Amazon chief executive Jeffrey Bezos is the owner of The Washington Post.)

Just ahead of E3, Google announced its own gaming video vertical, YouTube Gaming, seen by many as an attempt to take Twitch head-on. The Google site isn't due to officially launch until later this summer. But it still squared off with Twitch at the conference, reserving a big booth in the same hall. And though YouTube didn't stream nearly as much as Twitch, it did log 8 million viewers in its first 12 hours of broadcasting.

[Meet YouTube Gaming, Google’s answer to Twitch]

The showdown will be one to watch. YouTube, of course, is a streaming video juggernaut overall, with several high-profile gaming channels that draw millions of eyeballs. But Twitch has taken steps to cultivate goodwill within the community, hiring people from the e-sports and streaming communities onto its staff, as well as launching major charity efforts. (A promotion during E3 raised more than $390,000 for the Entertainment Software Association Foundation.)

In a statement, Marcus "djWHEAT" Graham, Twitch's director of programming, said, "We continue to be both appreciative and awestruck by the support we get from our passionate community. We credit them for not only tuning into hours and hours of E3 gaming goodness, but for bringing their own voice to the mix by co-streaming our broadcasts. When it comes to major trends coming out of E3, the appeal of live social video is definitely one of them."

Correction: This story has been updated to reflect that Amazon bought Twitch for $1 billion, not $1 million.