A depot is a logical grouping of files which are all delivered to a customer as a single group. Depots are uniquely identified by a Depot ID. When a customer installs an app, one or more depots are downloaded and "mounted" on their local drive, according to the rules outlined in the Depot Mounting Rules below.

Depot Mounting Rules

As described earlier, all content depots for a game are configured on the Depots page in App Admin. This includes all localized depots, add-on depots, DLC depots, etc. Without any other changes, all owned depots are mounted by default in the order listed. The depot's name can be anything and is not part of the mounting rules.
The depot order defines the mounting order, and files in depots that were mounted later override files in depots that were listed earlier. Thus the first depot in the list has the lowest priority. To change the depot order, you can drag and drop the depot entries around. To change fields, just click them.
The UI of the Depots page allows you to configure 4 different requirements.

• Language - Specifying a language for a depot will cause the depot contents to only download for users running Steam in that language. If your content should be available to users running in any language, use the default [All Languages] selection.
  
• OS - If this is set, the depot is only mounted on systems of given OS.
  
• Architecture - System Architecture: You only need to specify 32/64 bit architecture if you have separate depots for each. If you only have one depot, leave it set to [All Architectures]
  
• DLC - By default DLC depots and their content are managed under the base game AppID. If you want to offer a lot of different DLC depots for your product, turn on 'Manage DLC depots separately'. Then DLC depots are managed and uploaded separately under their own DLC AppID. This keeps the depot list for the base game short and reduces app meta data downloads by clients.

Shared Content Depots

If you have two applications that share content, it is possible include depots from a master application in another application. To add a depot from another application, go to Steampipe->Depots in the Steamworks Settings and click Add Shared Depot to browse for the depot you'd like to include (your account must have rights to modify Steamworks data on the app from which you are picking a shared depot).


Shared depots will inherit properties of the Master App from which they originate i.e. Language, OS, Architecture and DLC.



Once the depots are configured as shared, you can set the install folders to be the same between the two apps. This is required for the Steam client to keep only one copy of the content on the user's disk, but the install directories can be different if the shared depot content is small. Set the install directory on the General section under the Installation drop-down for your application's Steamworks Settings.

Operating System Depots

If your app supports multiple platforms, you should use separate depots to store the platform specific content. For example, if your app natively supports Windows and Linux, have any Windows-specific files in a depot that is marked just for Windows as a depot. Likewise, have any Linux-specific files in a depot that is marked just for Linux. You can then have any common set of files in a depot marked for both Windows and Linux, or All Oses if you like.

If you see a warning on your app landing page about an Operating System Depot missing from a package, that means you have an OS selected in the store data, and the package is missing at least one depot that can be mounted for that OS. Any users that own that package will not be able to download content for that OS. When this warning appears on your app landing page, you should probably correct it:



Shared depots, DLCs, or depots that contain the word "Debug" or "Internal" in their name will be excluded from this check. Most packages are checked, though any package with "For Beta Testing" or "Developer Comp" are excluded.