About STEAM

Steam is a digital distribution, digital rights management, multiplayer and communications platform developed by Valve Corporation. It is used to distribute games and related media online, from small independent developers to larger software houses; in October 2012, Valve expanded the service to include non-gaming software. Steam provides the user with installation and automatic management of software across multiple computers, community features such as friends lists and groups, cloud saving, and in-game voice and chat functionality. The software provides a freely available application programming interface, Steamworks, that developers can take advantage of to integrate many of Steam’s functions within their software products, including copy protection, networking and matchmaking, in-game achievements and micro-transactions, and support for user-created content through Steam Workshop. Though initially developed for use on Microsoft Windows, the client has expanded to include OS X and Linux versions, and clients with limited functionality on the PlayStation 3 console and for both iOS and Android mobile devices. In addition to being a central hub for gaming software, Valve has created a version of Steam with altered functionality to be used in schools for educational software, including a modified version of Portal 2 for teaching science and critical thinking lessons.

As of December 2012, there are nearly 2000 games available through Steam,[5] and 54 million active user accounts.[6] As of January 2013, Steam has seen over 6.6 million concurrent players.[7] Steam has an estimated 50–70% share of the digital distribution market for video games.[8][9]

The Steam logo is a stylised left-side fly-crank and rod from the Walschaerts valve gear of a steam locomotive.

 

Software delivery and maintenance[edit]

Steam’s primary service is to allow its users to download games and other software that they have in their virtual software library to their local computers. Steam-integrated games are stored as single non-compressed archive files with the extension .gcf (an acronym for game cache file).^[10] Steam allocates space on the user’s hard disk for .gcf files before downloading in order to reduce fragmentation which may occur when downloading large files and performing disk access. Game cache files help to make games more portable, stop users from accidentally overwriting important files, allow for easy modification of resources, and allows for validation of content for errors.^[11] For games that do not integrate, a “no cache file” system is provided. Here, a.ncf index file points to a directory of loose files somewhere else on the system.^[12] Users can enable Steam to automatically patch software packages as they are updated by their publishers, or alternatively allow users to manually initiate this patching process. The client allows users to back up game data files to other media, and remove game content files to free space on their machines.

Steam provides digital rights management (DRM) for software titles, by providing “custom executable generation” for executable files that are unique for each user, but allow that user to install the software on multiple computing devices via Steam or through software backups without limitations.^[13] As such, the user is required to have started Steam while connected to the Internet for authentication prior to playing a game, or have previously set up Steam in an “offline” mode while connected online, storing their credentials locally to play without an Internet connection.^[14] Steam’s DRM is available through Steamworks to software developers, but the service allows developers and publishers to include other forms of DRM and other authentication services on top of Steam; for example, some games on Steam require the use of “Games for Windows – Live“, and various 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 game saves and related custom files on Valve’s servers; users can then access this data from any other machine running the Steam client.^[15][16] Games must use the appropriate features of Steamworks for this feature to work. Users are able to disable this feature as well on a per-game and per-account basis.^[17] In May 2012, the service added the ability to manage their game libraries from remote clients, including other computers and mobile devices; users are able to instruct Steam to download and install games they own through this service if their currently running Steam client is active.^[18]

To protect against hijacking of accounts, Valve added Steam Guard functionality to the Steam client in March 2011. Steam Guard takes advantage of the identity protection provided with Intel’s second generation Core processors and compatible motherboard hardware to allow the user to lock their account to a specific computer. Once locked, activity by that account on other computers must first be approved of by the user on the locked computer. Support APIs for Steam Guard are available to third-party developers through Steamworks.^[19] An alternative option available to users interested in using Steam Guard istwo-factor, risk-based authentication, through the use of a one-time verification code sent to a verified email address associated with the Steam account. If Steam Guard is enabled on an account, the verification code is sent each time the account is used from a new machine.^[20] Many of Steam Guard’s features will work the same with the only real difference being the method of authentication.^[21]