The polycarbonate disc contains a spiral groove, called the "pregroove" (because it is molded in before data are written to the disc), to guide the laser beam upon writing and reading information. The pregroove is molded into the top side of the polycarbonate disc, where the pits and lands would be molded if it were a pressed (nonrecordable) Red Book CD; the bottom side, which faces the laser beam in the player or drive, is flat and smooth. The polycarbonate disc is coated on the pregroove side with a very thin layer of organic dye.