In chemistry, a carbide is a compound composed of carbon and a less electronegative element. Carbides can be generally classified by chemical bonding type as follows: (i) salt-like, (ii) covalent compounds, (iii) interstitial compounds, and (iv) "intermediate" transition metal carbides. Examples include calcium carbide (CaC₂), silicon carbide (SiC), tungsten carbide (WC) (often called simply carbide when referring to machine tooling), and cementite (Fe₃C), each used in key industrial applications. The naming of ionic carbides is not systematic.