The pages of a process's virtual address space can be in one of the following states.
| State | Description |
|---|---|
| Free | A free page is not currently accessible, but it is available to be committed or reserved. |
| Reserved | A reserved page is a block of the process's virtual address space that has been set aside for future use. The process cannot access a reserved page, and there is no physical storage associated with it. A reserved page reserves a range of virtual addresses that cannot be used subsequently by other allocation functions. A process can use the VirtualAlloc function to reserve pages of its address space and later to commit the reserved pages. It can use the VirtualFree function to release them. |
| Committed | A committed page is one for which physical storage (in memory or on disk) has been allocated. It can be protected to allow either no access or read-only access, or it can have read and write access. A process can use the VirtualAlloc function to allocate committed pages. The GlobalAlloc and LocalAlloc functions allocate committed pages with read-write access. A committed page allocated by VirtualAlloc can be decommitted by the VirtualFree function, which releases the page's storage and changes the state of the page to reserved. |