In a nutshell, DLP (Digital Light Processing) technology, also called DMD (Digital Micromirror Device), is based on the principle of reflection. The digital signal is interpreted as commands to micro-mirrors which either do or don't reflect the light coming from the projector lamp.
In 1987, Texas Instruments developed a reflector called DMD. The component has a matrix of 1.3 million microscopic mirrors set on pivoting heads that orient them to the light source. You could simply say that each mirror corresponds to one pixel of the image being projected. Since the base resolution of a matrix is 1280x1024, the result is a 1.3 million-pixel image. Projector manufacturers add a light source (the lamp) and a projection lens to the reflector. Together they make up DLP technology.