One of the major display technologies used in mobile phones. LCD displays have low energy requirements and are generally easy to read.
LCD panels generally consist of a grid of extremely tiny square areas called "pixels". Each pixel can be controlled to allow light to pass through, block it, or allow just a certain amount of light through. In a full-color LCD, each pixel contains at least three sub-pixels (red, green, and blue) that can be individually controlled. At a normal viewing distance, the sub-pixels appear as one pixel, which can be any color in the rainbow.
Color LCDs come in many types. TFT and TFD are several common technologies used. IPS is an improved variant of TFT.
Some older LCD displays used a technology called STN that had relatively poor color reproduction, poor viewing angles, and slow response time. These are no longer used in phones.
Traditional LCD technology is transmissive, meaning it's designed to allow or block light from a bright backlight. They have excellent brightness and saturation in low or medium light, but do not always work well in bright light.
Reflective displays are the opposite - they work best in bright light, but in dim light they rely on a "frontlight" instead of a backlight, which usually produces a "washed-out" look. Fully reflective LCD displays are uncommon.
Many modern LCD displays are "transflective", meaning they combine the properties of both transmissive and reflective displays. Transflective LCD displays have backlights that provide good brightness and color in dim and medium light, while also working well in bright light such as outdoors.