M2TS is the video stream packet format, MPEG-2 based, used on Blu-ray Discs. The normal extension is .m2ts, but in instances where such files are stored in filesystems (e.g., FAT32) that allow only three-letter extensions, .mts is used.
These files are usually accompanied by other associated files including these related formats:
- BDMV (Blu-ray disc files for user interactivity)
- CLPI (Blu-ray disc clip info files)
- MPLS (Blu-ray disc playlists)