A seal is a device that prevents leakage between two objects and retains system pressure. Seals can be either static or dynamic seals. Static seals are placed between two non-moving parts. Examples include integral seals and press-in-place (PIP) seals. Dynamic seals are placed between two moving parts. Examples include shaft seals, and hydraulic cylinder seals.

Gaskets are seals used to prevent the flow of fluid between two surfaces. They retain lubrication, keep out dirt and other foreign materials, and isolate (or separate) different gases, liquids, or solids. A gasket is a type of a static seal that fills the space between two mating parts to prevent leakage at the mating surfaces. Gaskets are designed to be pressed between two stationary faces with enough pressure to force the gasket material into all of the surface irregularities of the mating surfaces. Gaskets are used in a variety of products from automobile engines to electronic housings. They are required to seal against outside elements and prevent fluid leakage.