TES File

A TES file is a saved data file used by The Elder Scrolls IV: Oblivion, The Elder Scrolls V: Skyrim, and Fallout 4.

About
It contains game save data that is applied to an associated .ESP, .ESM, or .ESL file and used to maintain changes a player makes to the games' in-game environment.

In addition to TES files created by the games mentioned above, modders may encounter TES files created by the Bethesda Softworks Creation Kit. On rare occasions, Creation Kit saves ESP, ESM, or ESL files that a modder is working on as TES files. To correct this error, rename the incorrectly-saved TES file to use the .esp, .esm, or .esl extension.