Final answer:
Extrusion is a manufacturing process used to create objects with a fixed cross-sectional profile. The layers around the extrusion provide structural support and protection.
Step-by-step explanation:
Extrusion is a manufacturing process used to create objects with a fixed cross-sectional profile. It involves pushing a material through a die of the desired shape. For example, in metal extrusion, a billet of metal is squeezed through a die to create a long metal rod or pipe with a specific cross-section.
The layers around the extrusion refer to the material that is surrounding the extruded object. These layers can provide structural support and protection to the extrusion. For example, in the case of plastic extrusion, the layers around the extruded plastic profile can provide additional strength and integrity to the final product.