Memory-Mapped File

A memory-mapped file is a segment of virtual memory that has been assigned a direct byte-for-byte correlation with some portion of a file or file-like resource.

Saw this from Boost - https://www.boost.org/doc/libs/1_84_0/doc/html/interprocess/some_basic_explanations.html

Mapping a File into Memory: When a file is memory-mapped, its contents are mapped into the virtual address space of a process. This means that the file appears as if it were part of the process’s memory, allowing the application to read and write to the file using memory operations instead of traditional file I/O system calls.