A COM file is a type of simple executable file used historically by MS-DOS and early versions of Microsoft Windows. The name is derived from the 'command' filename extension, and it represents one of the oldest executable formats in the PC ecosystem. Unlike the more modern and complex EXE (Executable) format, a COM file is a raw binary image that contains no headers or metadata; the operating system simply loads the file into memory and begins execution at the first byte. Due to the architectural constraints of the 16-bit x86 real mode, COM files are strictly limited to a maximum size of 64 KB, as the code, data, and stack must all reside within a single memory segment. While modern 64-bit versions of Windows no longer support 16-bit COM files natively, they remain highly significant in the history of computing and are still frequently encountered in legacy systems, embedded environments, and when using DOS emulators.