Steam Cloud

Steam Cloud is a cloud storage service that is a component of SteamWorks. It enables data to be uploaded, backed up, and restored from the Internet. This can include game progress and configuration such as resolution, audio and controls.

The feature was initially shipped with Left 4 Dead, and has since become available to all developers using the SteamWorks API.

There are currently games documented on  that have Steam Cloud support. A full list can be found here.