3. CRT Projector
 A CRT projector is a video projector that uses a
small, high-brightness cathode ray tube as the image
generating element. The image is then focused and
enlarged onto a screen using a lens kept in front of the
CRT face.

4. LCD Projector
 An LCD projector is a type of video projector for
displaying video, images or computer data on a screen
or other flat surface.

5. DLP Projector
 Digital Light Processing is a type of projector
technology that uses a digital micro mirror device.

6. Lumens (unit)
 A measure of the total amount of visible light emitted
by a source.

7. Throw
 Throw is the distance of a movie projector from the
screen

8. Lamp
 A lamp is in a projector and it produces the light for
the image.