Which Infinity Stone is contained in the Tesseract?

The Infinity Stone contained in the Tesseract is the Space Stone. The Tesseract is a blue, cube-shaped containment device that holds the glowing blue gem and channels its power.

In the MCU, the Space Stone controls space. It can create portals, enable instantaneous travel between distant locations, and generate enormous amounts of energy. The Tesseract is used by the Asgardians to help power the Bifrost, while humans and Hydra study it as a potential energy source and weapon.

The object appears throughout the Infinity Saga, including Captain America: The First Avenger, The Avengers, and Avengers: Infinity War. In the latter, Thanos removes the Space Stone from the Tesseract and places it in the Infinity Gauntlet. A common mistake is to treat the Tesseract itself as the Infinity Stone; technically, the cube is the container and the Space Stone is what lies inside it.