Tin is a chemical element in the periodic table that has the symbol Sn (Latin: stannum) and atomic number 50. This silvery, malleable poor metal that is not easily oxidized in air and resists corrosion is found in many alloys and is used to coat other metals to prevent corrosion. Tin is obtained chiefly from the mineral cassiterite, where it occurs as an oxide. It is the classic alloying metal to make bronze.

Elemental tin is an essential nutrient, needed in very small amounts. However, certain organic tin compounds, organotin, such as triorganotins (see tributyltin oxide) are toxic and are used as industrial fungicides and bactericides.