Here’s a little clarity… Do you remember those ASAHI watches we used to buy for 50 BOB? That is an LCD (Liquid Crystal Display) screen. Any screen you see using LCD tech is just like that watch (just a little advanced for better refresh rate and a bunch of other stuff.) Do you recall the ‘bulb’ used on most rechargeable torches that doesn’t look like a miniature traditional light bulb? That is an LED (light emitting diode.) Most can not only produce white light but also any other color.
These are the two most commonly used materials for screens.
Now, an LCD screen only produces images but no light. That’s why it must have a backlight for the images and colors to be visible. Most old LCD displays used a CCFL as @Deno05 said. This is basically a long fluorescent tube put at the edges of the screen to light up the display. The LCD usually has a white material stuck on the back to ensure even light distribution but it’s far from perfect. LED backlit screens use an array of white LEDs put directly behind or at the edges of the screen to illuminate it. The picture quality on LCD screens is okay but it cannot match that of an OLED screen.
An OLED (organic light emitting diode) screen uses LEDs to display the picture. It’s not called organic because it uses natural materials but because each pixel produces its own light. This type of screen doesn’t need a separate backlight. Its pictures are extremely vivid because it completely turns off the pixels on black parts of the picture. In contrast, a LCD screen will always look grey when the picture is black because the backlight illuminates all pixels indiscriminately.