Required DLL files are then mapped (this includes custom libraries in addition to system libraries such as and ):

The process then starts executing bytes in the EXE file. However, the only way the process can use or set values in its VAS is to ask the OS to map them to bytes from a file. A common way to use VAS memory in this way is to map it to the page file. The page file is a single file, but multiple distinct sets of contiguous bytes can be mapped into