In a virtual address space, at any given time, each page can be classified as:

   free / reserved / committed

Pages that are committed are further classified as:

   present in physical memory / swapped out to secondary storage

   in user space / in kernel space

   shared page / private page

   read only page / read-write page / copy-on-write page

   page is "dirty" (modified) / page is clean

   page has been "accessed" / page has not been "accessed"

   backed by a file / backed by the swap space

   backed by an executable file / backed by a "data" file