A D64 file is a disk image format commonly associated with the Commodore 64 (C64) home computer. It's essentially a digital representation of a 5.25-inch floppy disk used by the C64. These files contain the complete contents of the disk, including the operating system (Commodore DOS), programs, data files, and any other information stored on the original physical disk. D64 images are used for archiving, distributing, and emulating C64 software. Emulators like VICE and CCS64 can load and run D64 files, allowing users to experience C64 software on modern computers. The format preserves the original disk structure and data, ensuring accurate emulation. D64 files are a crucial part of preserving the legacy of the Commodore 64 and its vast library of software.