HF stands for hydrogen fluoride, which is an inorganic compound with the chemical formula HF. It is a colorless gas or liquid that dissolves in water to yield an aqueous solution called hydrofluoric acid. HF is diatomic in the gas-phase, and as a liquid, it forms relatively strong hydrogen bonds, which explains its relatively high boiling point. Solid HF consists of zig-zag chains of HF molecules, and liquid HF also consists of chains of HF molecules, but the chains are shorter, consisting on average of only five or six molecules.

HF is widely used in various industries, including the manufacture of refrigerants, herbicides, pharmaceuticals, high-octane gasoline, aluminum, plastics, electrical components, and fluorescent light bulbs. It is also used for etching glass and metal. HF is produced by reacting a naturally occurring mineral, fluorspar, with sulfuric acid.

HF is an extremely toxic and corrosive gas and liquid that can irritate the eyes, nose, and respiratory tract even at low levels. Safety is a primary concern for both producers and users of HF, and there are recommendations on the safe handling of hydrofluoric acid during production, storage, transportation, and use.