The Tesseract, also known as the Cosmic Cube, is a powerful artifact in the Marvel Cinematic Universe that has played a significant role in many of the franchises films. It is a crystalline cube-shaped containment vessel for the Space Stone, one of the six Infinity Stones that predate the universe. The Tesseract was created by a cosmic entity known as the Beyonders, who are a race of God-like beings that possess immense power and can manipulate the very fabric of reality. They created the Tesseract as a tool to harness their power and control the universe.

The Tesseract first appeared in the post-credit scene of Thor, where it was shown to be in the possession of S.H.I.E.L.D. director Nick Fury. Fury recognized the cubes immense power and suggested it could be used as an unlimited energy source. The Tesseract has played a vital role in the franchises overarching storyline, as it is revealed to be one of the six Infinity Stones, powerful artifacts that grant immense power to their wielders. It is specifically the Space Stone, which allows its possessors to manipulate space and travel across vast distances instantly. We saw its ability in Avengers: Infinity War when Thanos used it with other infinity stones to destroy half of all life in the universe with a single snap of his fingers.

In summary, the Tesseract is a powerful artifact in the Marvel Cinematic Universe that contains the Space Stone, one of the six Infinity Stones. It was created by the Beyonders as a tool to harness their power and control the universe. The Tesseract has played a significant role in many of the franchises films and has been a source of curiosity for Marvel fans.