If you're a big PC gamer, there's absolutely no way you haven't heard of Steam. Valve's platform has gone from an interesting way to buy games to basically the dominant force in the market, over the course of a couple of decades.

What is Steam?

Steam is Valve's PC gaming platform - it's first and foremost a storefront and library through which you can buy a frankly mind-boggling variety of PC games.

However, over time it's grown to account for much more than just buying games, with a huge social side that lets you make parties and friends lists in-game, page after page of discussions about different titles, and a range of different ways to actually play the games you own.

Valve is the company behind Steam, and it started as the developer of classics like Half-Life and Portal, but launched Steam to have more control over the digital distribution of its games. It struck gold and has grown into an absolutely massive publisher, curator, moderator and sales engine as a result.

Steam also offers a few ways to play games not on your PC - including a remote play system called Steam Link that lets you cast your game to other displays like your TV while still powering things from your hardware. The Steam Deck, meanwhile, has seen it jump into the world of handheld gaming, its biggest hardware success ever.

How to install Steam?

The core of Steam lies in its various apps for different platforms - you can install Steam on your PC, Mac, iPhone or Android device to access the service.

While PC and Mac versions of Steam will also let you launch and play games, the apps on mobile devices are a little more restrictive, but you can still browse the store, talk to friends or strangers and use most of Steam's other social features with them.

You can download Steam for PC, Mac or Linux here, check it out on the Apple App store here, or the Google Play Store here.

How much does Steam cost?

Here's the good news - Steam is completely free. It's a storefront, not a subscription service, so you can create a Steam account without having to give any money to Valve at all.

This means you can play free-to-play games available through Steam easily, and if you do want a paid-for title, you can just head to the store and pick it up before downloading it to play.

What games are on Steam?

This is where things get mind-boggling - for services like Xbox Game Pass we're able to keep a running list of every title on the service, because they number in the hundreds.

In the case of Steam, the number of games available to buy runs in the tens of thousands, and hundreds of games get added every day as developers fight for attention.

So, it's more a question of what games aren't on Steam than which ones are - there are some big exceptions. Fortnite, for example, isn't on Steam because its creator Epic Games has a rival store that it would prefer people to use. It's the biggest missing link, but other Epic Games titles like Rocket League are also missing for the same reason.