In an internal combustion engine, the cylinder head sits above the cylinders and consists of a platform containing part of the combustion chamber and the location of valves and spark plugs.

In the overhead valve head, the top half of the cylinder head contains the camshaft in an overhead cam engine, or another mechanism (such as rocker arms and pushrods) to transfer rotational power from the crankshaft to linear power to operate the valves (pushrod engines perform this conversion at the camshaft lower in the engine and use a rod to push a rocker arm that acts on the valve).

The number of cylinder heads in an engine is a function of the engine configuration. A straight (or inline) engine has only one cylinder head. A V engine usually has two cylinder heads, one at each end of the V.