Carbide is a polyatomic ion consisting of two carbon atoms or any salt containing such an ion. The ion carries a -2 charge.

Under conditions of standard temperature and pressure, metal carbides react strongly with water to form metal oxides or hydroxides and flammable acetylene gas.

Carbide lamps, an important source of portable subterranean illumination for mining and spelunking, work through on-demand production and combustion of acetylene by the metered addition of water to calcium carbide.