LCDs, or commonly known as Liquid Crystal Displays, were partially responsible for the first laptop. Before LCD screens, "laptops" or portable computers as they were called, were large and cumbersome. The LCD screen allowed the laptop to be small and functional. 

When the LCD was first invented, it was used for watches. Then came grocery store screens. Then came clocks. Finally, some enlightened fellow decided to miniaturize LCDs, and the LCD screen/monitor was born. That’s right, the LCD on your favorite toy or electronic is the same technology used in laptop screens (LCDs). There are two LCD technologies used in laptops today. They are both very similar in the application, but each possesses their own unique qualities. Here they are the active and passive matrixes.

Active Matrix
 

The Active matrix screen is composed of thousands of LCDs with a small transistor attached behind them. When the video adapter gives the instruction to light a particular pixel, the transistor sends electricity through two electrodes, which "light the LCD". There is a few ups and downs surrounding the active matrix technology. The upside to the story is that the picture produced is very clear and easy to see. On the downside, the active matrix design uses an immense amount of power. Therefore shortening the time available for batter powered laptop.

Passive Matrix
 

The Passive matrix screen is like a giant gridwork of LCDs surrounded on the outside by transistors. When, the video adapter requests a certain image, the LCDs are lighted by sending a current through two intersecting wires. The gridwork of wire stretches across the entire screen, and where they intersect, the LCD lights up. There is one main drawback in the passive matrix design. The time that it takes to make the required intersections causes a poor refresh rate. This slow refresh rate is commonly referred to as the submarine effect. That is, when the user moves the mouse rather rapidly, the mouse seems to disappear and then reappear on the other side of the screen.