An optical drive is usually a CD drive or DVD drive. Optical means it uses lenses. The drive uses a light called a laser. A laser is the most exact and powerful sort of light but the laser in the drive is very, very small. The CD or DVD disk is similar to a mirror and the laser light reflects off it. The disk has very small () codes written on it. The drive has a very small camera lens beside the laser which can read the codes. Another part of the drive is plugged in to the computer by a wire (inside) and the code goes through the wire as a signal to the computer. 