Shared memory can best be described as the mapping of an area (segment) of memory that will be mapped and shared by more than one process. This is by far the fastest form of IPC, because there is no intermediation (i.e. a pipe, a message queue, etc). Instead, information is mapped directly from a memory segment, and into the addressing space of the calling process. A segment can be created by one process, and subsequently written to and read from by any number of processes.