"Collect core files dropped by killed enemies and deliver them to the Fracture Site."
— Official description.
Fracture is a game mode featured in Call of Duty: Black Ops III. It was released on 15th July, 2016, shortly after the release of the Descent DLC pack.
Enemies killed in this game mode drop data fragments, which can be collected and deposited at the "Fracture Site" for points. It is similar to the Private Match, and a Local multiplayer-exclusive game mode "Grind" in Call of Duty: Ghosts.