Types of Memory

Anonymous Memory
Non-persistent memory
Allocated by malloc
Used for private copies of file data, etc.
Can be shared between processes
Changes by one process will be seen by others
Paged to swap

Mapped Memory
Memory associated with a region on a disk, in a file, etc.
Read-only access can be shared
Paged to the associated backing store

Copy On Write
Private memory which is logically shared (i.e. sharing read/write access)
Reduces copying
Maps (e.g. bss) can be shared between two processes, copy is made on demand
Fork makes a copy of the entire process, however, most memory is never actually touched