Save all virtual objects to disk prepares the website for deployment. The objects using VirtualPathProvider will be saved to the disk to allow the pre-compilation of the website. Please note that you may need to manually delete some files if you changed the object code names or deleted the objects between two deployments. It actually stores the physical files to the system, what is in need to run the site properly under the Medium trust Environment.

Page url: http://devnet.kentico.com/docs/5_5r2/contexthelp/index.html?deployment_tab.htm