For many people, the recent rumours that online video firm Twitch might be bought by Google for $1bn were the first they'd heard of the company and the world of professional video game competition – or eSports – that has fuelled its growth.
A new report from research firm IHS Technology suggests that eSports was far from a niche interest last year, however. The company claims that the number of eSports viewing hours grew from 1.3bn in 2012 to 2.4bn in 2013.
That's 2.4 billion hours of people watching other people play games, either online through services like Twitch and its rivals, or on traditional TV channels.
"eSports videos have rapidly transformed from a niche activity into a widely-watched, global, cross-platform entertainment category," said Dan Cryan, senior director of digital media research at IHS, and author of the report.
The report picks out League of Legends, Dota 2 and StarCraft II as the most popular games being watched, with Cryan suggesting that several factors have led to the rapid growth in eSports viewing around the world.
"Key game titles have reached maturity and game publishers are taking a major role in promoting esports competitions. Furthermore, esports viewing has been boosted by the emergence of online video platforms that are capable of handling large-scale live audiences," he said.
Twitch isn't the only example – its rivals include Azubu and MLG – but it may well be the biggest. The company more than doubled its monthly audience from 20m people at the end of 2012 to 45m at the end of 2013, watching 106 minutes a day on average.
Its biggest audience came in October, with 32m people watching the League of Legends Season 3 World Championship event in a single day.
IHS claims that 2013 was the first year when online viewing of eSports exceeded television viewing. By 2018, when the company expects eSports viewing to reach 6.6bn hours a year, it predicts that 90% of this will happen online rather than on TV.
By then, the distinction between the two may well have disappeared, if more people are streaming video from services like Twitch to their televisions.
IHS thinks that games companies will be able to capitalise financially on this boom in eSports viewing, mainly through advertising. The company expects the category to attract $300m of online advertising revenues in 2018, for example.
eSports is already a significant business, with brands like Coca-Cola and American Express already sponsoring the biggest tournaments.
That's translating into more money for the best players: this year's Call of Duty World Championships had a prize purse of $1m, including $400k for the winning team.
eSports is not the only proof that watching games is an increasingly popular leisure activity. Gaming is one of the biggest categories on YouTube alongside music, for example.
The most popular YouTube channel in the world belongs to gamer Felix Kjellberg, whose PewDiePie channel has 27.4m subscribers and 4.6bn video views so far, adding 296.6m of those in April 2014.
Meanwhile, there's a massive pre-teen and early-teen audience for YouTube channels focusing on just one game, Minecraft.
Analysis by The Guardian in March 2014 found that four UK-based YouTube channels focusing mainly or entirely on Minecraft – Stampy, The Diamond Minecart, iBallisticSquid and Yogscast – collectively generated 343.2m views in February alone.
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