Game streaming — people watching other people play videogames — is big business. Twitch.tv, the epicenter of game streaming, was sold to Amazon ($AMZN) last year for a healthy $1 billion. That's because at any moment, Twitch.tv has thousands of live streams featuring hosts playing games as others watch. Streaming channels include not just live video, but also community interactions such as live chat giveaways, tips, contests, and more.

This is no hobby. It's big, big business. Streamer Tyler "Ninja" Blevins, who has more than 5 million followers on his Twitch and YouTube channels, recently told CNBC that he pulls in $500,000 per month playing "Fortnite," a new game that has taken gaming — and streaming — by storm, as we've reported.

As huge as videogame streaming already it, hourly Twitch.tv channel traction usage data that we track suggests the phenomenon is still in its early stages, and it's poised for exponential growth.

In April 2016, an average hour on Twitch.tv featured around 500,000 active streams. That's already a massive number. But as of today, that average number is eclipsing twice that amount.

At the same time, the diversity of content is exploding. Games streamed over past 200 days have increased 30%, from a daily 105,000 games to 135,000 games.

It's likely streaming's growth will continue, and possibly snowball. Most people play videogames, and watching others play is a chance to watch skilled players show the ropes. In other cases, streaming channels are simple nostalgia affairs in which charmismatic channel hosts play through classic games in a more relaxed atmosphere.

As more games are streamed and a more diverse set of hosts take to the digital airwaves, it's pretty clear that game streaming is still in its infancy.