A configuration is a set of document versions, which are grouped together in order to make them easier to recover. Configurations can be useful for grouping model versions that have dependencies between them (for example, through generation links or shortcuts) or documents that represent a particular point in your development, such as a release. You can easily check out all the documents included in the configuration.
In the following example, the versions used for a minor release are circled, and are included in a configuration called Minor Release: