Memory-mapped file
Virtual memory region with bytes mapped to a file or file-like resource / From Wikipedia, the free encyclopedia
Not to be confused with Memory-mapped I/O.
A memory-mapped file is a segment of virtual memory[1] that has been assigned a direct byte-for-byte correlation with some portion of a file or file-like resource. This resource is typically a file that is physically present on disk, but can also be a device, shared memory object, or other resource that an operating system can reference through a file descriptor. Once present, this correlation between the file and the memory space permits applications to treat the mapped portion as if it were primary memory.