What elements is chrome made up of, and how is it made?

Chrome plating is a finishing treatment utilizing the electrolytic deposition of chromium. The most common form of chrome plating is the thin, decorative bright chrome, which is typically a 10 µm layer over an underlying nickel plate.

There are two types of chromium plating: industrial and decorative.

Hexavalent chromium baths whose main ingredient is chromic anhydride.

Trivalent chromium baths whose main ingredient is chromium sulfate or chromium chloride. Trivalent chromium baths are not yet common, due to restrictions concerning color, brittleness, and plating thickness.

https://en.wikipedia.org/wiki/Chrome_plating