How are DVDs manufactured?

A DVD is about 1.2 millimeters thick and is composed of plastic layers created by injection molding polycarbonate plastic, according to HowStuffWorks. The resulting disc has a continuous spiral track of microscopic bumps as data.

After the polycarbonate plastic bumps are in place, a reflective layer is added onto the DVD that covers the bumps. The reflective layer behind the inner layers is composed of aluminum. For the outer layers, semi-reflective gold is used, which enables a laser to focus through all of the layers of the disc. Lastly, the layers are coated with lacquer, compressed together and treated with infrared light.