Re: how does a computer monitor work ?

Most desktop displays use a cathode ray tube (CRT), while portable computing devices such as laptops incorporate liquid crystal display (LCD), light-emitting diode (LED), gas plasma or other image projection technology.
Typically, your computer takes the digital data sent by application programs, stores it in video random access memory (VRAM) or some equivalent, and uses a digital-to-analog converter (DAC) to convert it to analog data for the display scanning mechanism. Once it is in analog form, the information is sent to the monitor through a VGA cable.
A VGA connector has three separate lines for the red, green and blue color signals, and two lines for horizontal and vertical sync signals. In a normal television, all of these signals are combined into a single composite video signal. The separation of the signals is one reason why a computer monitor can have so many more pixels than a TV set.
Anyway, here is a website that explains in more detail how a computer monitor works: How Stuff Works: Computer Monitor