Matroska Video, a flexible, open-standard video container format that can hold a high number of video, audio, picture, or subtitle tracks in one file [1].

Use tools like CloudConvert if the file is small. 4. Troubleshooting

Because MKV files can use various codecs, you need a player that supports a wide range of formats.

(e.g., Telegram download, email attachment?) What device are you trying to play it on?