The .x64 file extension is primarily associated with the Commodore 64 (C64) emulator disk image format. It is a specific type of container used by the VICE (Versatile Commodore 8-bit Emulator) software to represent the contents of a physical 5.25-inch floppy disk used by the vintage Commodore 64 computer system. Unlike the more common .d64 format, which is a raw sector-by-sector copy of a disk, the .x64 format was an early attempt to provide a more structured or extended version of disk images, though it has largely been superseded by .d64 and .g64 formats in modern emulation circles. These files contain the binary data of games, applications, or operating system files originally designed for the MOS Technology 6510 processor. When loaded into an emulator, the software treats the .x64 file as a virtual drive, allowing users to load and execute legacy software on modern hardware. It preserves the file structure and data integrity of the original media, enabling the preservation of computing history and retro gaming experiences across various operating systems. Because it is a legacy format, it is less common today than the standard D64 format but remains compatible with most major C64 emulation suites.