The head gasket is compressed between the engine block and the cylinder head.

The head gasket seals in the internal combustion process and also keeps coolant and oil from mixing together as the two fluids travel from the engine block to the cylinder head.

A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression.

A Gasket is a deformable material that is used to create a static seal and maintain that seal under various operating conditions in a mechanical assembly.

Gaskets allow for "less-than-perfect" mating surfaces on machine parts where they can fill irregularities. Gaskets are commonly produced by cutting from sheet materials.

Gaskets for specific applications, such as high pressure steam systems, may contain asbestos. However, due to health hazards associated with asbestos exposure, non-asbestos gasket materials are used when practical.