Valve decided to create a platform that would update games automatically and implement stronger anti-piracy and anti-cheat measures.
Valve also recognized, through user polls at the time of its announcement in 2002, that at least 75% of their users had access to high-speed Internet connections, which would only grow with planned Internet expansion in the following years, and recognized that they could deliver game content faster to players than through retail channels.
Steam was an optional component for all other games.
Developers are not limited to Steam's CEG and may include other forms of DRM and other authentication services than Steam; for example, some titles from publisher Ubisoft require the use of their UPlay gaming service, In September 2008, Valve added support for Steam Cloud, a service that can automatically store saved game and related custom files on Valve's servers; users can access this data from any machine running the Steam client.
In May 2012, the service added the ability for users to manage their game libraries from remote clients, including computers and mobile devices; users can instruct Steam to download and install games they own through this service if their Steam client is currently active and running.
By November 2015, the service had as many as 12.5 million concurrent users and had over 125 million registered accounts.
In 2015, users purchasing titles through Steam or through Steam keys from third-party vendors totaling around $3.5 billion representing 15% of the global PC game sales for the year, based on estimations made by the tracking website Steam Spy.
The software provides a freely available application programming interface (API) called Steamworks, which developers can use to integrate many of Steam's functions into their products, including networking, matchmaking, in-game achievements, micro-transactions, and support for user-created content through Steam Workshop.
Though initially developed for use on Microsoft Windows, versions for OS X and Linux operating systems were later released.
Once the software is downloaded and installed, the user must then authenticate through Steam to de-encrypt the executable files to play the game.
Normally this is done while connected to the Internet following the user's credential validation, but once they have logged into Steam once, a user can instruct Steam to launch in a special offline mode to be able to play their games without a network connection.
Valve's Half-Life 2 was the first game to require installation of the Steam client to play, even for retail copies.
This decision was met with concerns about software ownership, software requirements, and issues with overloaded servers demonstrated previously by the Counter-Strike rollout.
Initially, Valve was required to be the publisher for these titles since they had sole access to the Steam's database and engine, but with the introduction of the Steamworks software development kit (SDK) in May 2008, anyone could potentially become a publisher to Steam, outside of Valve's involvement to curate titles on the service.