A rear projection television is named because, unlike other televisions, the image is projected from behind the screen. The reflection provided is the actual picture you see on the screen. There are many components needed for the rear projection television to work properly. The lenses and assembly of the lenses used to magnify a projected image, the mirror that the projection itself if reflected from and the screen that shows the resulting image. All components are essential to the proper working of a rear projection television. 
The various projection technologies commonly used today in rear projection televisions are CRT, LCD, and DLP.

The CRT, or Cathode Ray Tube projection system, was the basis for the rear projection television itself. The CRT utilizes three small Cathode Ray Tubes, one for each of the primary colors, to give the projection its high quality picture. A CRT tube is a large vacuumed tube that emanates an electron beam from a single point in the tube. The beam, after touching the face of the tube, lights up phosphors on the tubes surface to create the image.

The CRT, one of the oldest rear projection televisions, is cheap by comparison to many other newer televisions and provides a wide range of vibrant colors. However, the CRT projection television is quite large in cabinet depth, in comparison to LCD, Plasma, and even DLP and LCD rear projection televisions. A CRT television also has to be converged properly for proper image reproduction, if it is not the tubes may be out of alignment, causing color halos or color distortion.
The LCD or Liquid Crystal Display uses white light passed through small cells filled with liquid crystal. Each pixel is composed of three cells: red, green, and blue. An electrical charge manipulates these cells, creating intensity of colors. The LCD television has arguably one of the best picture projections of the three rear projection televisions. Because the chip is very tiny, the panel for the LCD rear projection television can be made very thin and light unlike the CRT projection television. Although they are not as small as the plasma flat panel televisions, they can still save floor space. They are also less expensive as the plasma technology and come with brighter, wider screens and offer more contrast.
The DLP, Digital Light Processing, television is like the LCD in the way that the image is displayed. Like LCD, the actual image is displayed on a chip; however, the DLP chip is very different from that of an LCD chip. The DLP projection chip, known as a DMD or Digital Micromirror Device, is very simply a reflective mirror.

DLP projection has excellent color accuracy, it is compact, has low power consumption, and high contrast and brightness. Although the DLP has excellent picture, it can show a “rainbow effect”. The “rainbow effect” is a brief flash of colors like a rainbow exhibited when you look quickly side to side on the screen. The DLP chip is also lit by another light source, meaning periodic replacement of its light source, which can be very expensive.