There are lot of display types used in mobile phones. They can be either color or monochrome. Monochrome displays on the other hand can be alphanumeric or graphic. Alphanumeric displays can show only symbols with a constant size, while graphic displays can show fonts of different sizes and animations.
The color displays usually are CSTN, TFT, TFD or OLED with a predominant use of TFT displays in current mobile lineups. There are also two types of touchscreen displays - capacitive and resistive, which are both based on TFT technology.
CAPACITIVE touchscreens work by sensing the electrical properties of the human body, while RESISTIVE ones operate by sensing direct pressure applied by the user.
The RESISTIVE type can be activated by pressing not only with human skin but also with a stylus and thus allow handwriting recognition input.