In-Place Compilation : In-place precompilation allows a developer or a site administrator to access each page in the application as if it were being used by end users. This means each page is compiled as if for ordinary use. In-place precompilation takes place after the site is deployed but before it goes public. To precompile a site in-place, you use the following command, where /core35 indicates the virtual folder of the application: aspnet_compiler –v /core35 Precompilation for Deployment : Precompilation for deployment generates a .le representation of the site made of assemblies, static .les, and con.guration .les—a sort of manifest. This representation is generated on a target machine and can also be packaged as MSI and then copied and installed to a production machine. This form of precompilation doesn’t require source code to be left on the target machine. aspnet_compiler [-?] [-m metabasePath | -v virtualPath [-p physicalPath]] ...