Extrusion coating and laminating developed during the 1940s in the United States and was introduced to the United Kingdom on a commercial scale about a decade later. By the use of extrusion coating it is possible to combine the desired properties of the substrate and of the coating medium. Common substrates are paper, board, tissue, fabric, film and foil and the vast majority of coating and laminating media are polymeric plastics of which low density polyethylene is the one most often used. However, medium and high density polyethylene, polypropylene and other less common polymers are becoming increasingly used. By the judicious choice of the substrate, coating medium and machine conditions it is possible to develop packaging materials and other membranes with whatever combination of properties are required—barrier properties against moisture greases or gases, appearance, handle etc. Perhaps the most important basic properties when considering any particular polymer for extrusion are Melt Index and Density and the machine variables most likely to affect the final product are melt temperature, die-nip distance and nip roll pressure. Common uses for extrusion coated and laminated products are outlined showing how the materials are used for packaging and to provide membranes generally throughout industry from consumer packaging through to the building trade. Special mention is made regarding how extrusion can save resources and hence money for the user.