LCD stands for Liquid Crystal Display. Computer LCD monitors uses this technology to display images on the screen. Nowadays lcd monitors are quickly replacing the older CRT monitors because of its ease of use and far better technology. Computer LCD monitors consume very less space and electricity considered to the CRTs. Because of this they are used in different electronic devices as well such as laptop computers, watches, calculators, mobiles, portable media players, telephones etc. They are availabe in wide variety of screen sizes than CRTs. In computer LCD monitors each individual pixels is divided into three subpixels which are coloured red, green and blue respectively. And each subpixel can be controlled independently to give thousands and millions of colours for that individual pixel. Each subpixel has its own dedicated transistors to control the shades of color to display. The subpixels are made up of a liquid crystal molecules. The liquid crystal molecules are suspended between transparent electrodes and are sandwiched between two polarising filters. Some important features to remember are : Contrast ratio : <br>It is defined as the ratio of luminance of the brightest color(white) to that of the darkest color(black) that the system can produce. A high contrast ratio results in sharper and better image quality. Experts recommend contarst ratio of 500:1 or greater than that for better picture quality. Viewing Angle: <br> It is the maximum angle at which a display can be viewed without the picture being washed out. The display becomes blurry and faints outside the viewing angle. Viewing angle is measured both horizontally and vertivally. The greater the viewing angle the better. CRTs have viewing angle of 180 degrees. Response Time: <br>It is defined as the minimum time needed to change the color or brightness of a pixel. Response time is measured as the time taken by a pixel to turn black to white and then back to black again. The lower the response time the better will be the LCD. If the response time is greater than it forms blurry images or moving objects because the pixels take longer duration to change its color or brightness. Response time is measured in milliseconds(ms). Aspect Ratio: <br> It is defined as the ratio of the width to the height of the display screen. CRT monitors use 4:3(portrait view) aspect ratio. But the laptops and modern LCD monitors use aspect ratio of 16:9 or 16:10(landscape view).