Plastic injection moulding is a manufacturing process for producing parts by injecting molten material (resin) into a mould. Material for the part is fed into a heated barrel, mixed (using a helical screw), and injected into a mould cavity, where it cools and hardens to the configuration of the cavity.  After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mould-maker (or toolmaker).

Plastic injection moulding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars. And it uses a special-purpose machine that has three parts: the injection unit, the mould and the clamp. Parts to be injection-moulded must be very carefully designed to facilitate the moulding process; the material used for the part, the desired shape and features of the part, the material of the mould, and the properties of the moulding machine must all be taken into account. The versatility of injection moulding is facilitated by this breadth of design considerations and possibilities.