How Windows System Image Manager Works
Windows System Image Manager (Windows SIM) is the tool used to create unattended Windows Setup answer files. The creation of an answer file is achieved by using information from a Windows image (.wim) file and a catalog (.clg) file. Component settings are added to a configuration pass in the answer file. You can also add packages to be installed during Windows Setup.
Distribution shares and their more portable counterparts, called "configuration sets," store files and folders that enable additional customizations of Windows installations.