The T64 file format is a disk image format used primarily for Commodore 64 software. It's a container format that stores the contents of a Commodore 64 cassette tape. These tapes were a common method of storing and distributing software for the C64. A T64 file typically contains one or more programs or data files that were originally stored on the tape. The format includes header information that describes the files contained within, such as their names, load addresses, and execution addresses. Emulators use T64 files to load and run Commodore 64 software on modern computers. The T64 format is relatively simple compared to other disk image formats like D64 (for floppy disks), but it's effective for preserving and distributing tape-based software. It's widely supported by Commodore 64 emulators and is a popular choice for archiving and sharing classic C64 games and applications. The format is designed to be a direct representation of the data on the original tape, allowing for accurate emulation of the loading process.