Colourful Pixel in the Ice-cream Van

A colourful pixel is two or more tiny LEDs with different colour put very closely. When some LEDs are on, others are off, or all are on, you will see a different colour thinking it is only one pixel.
A touchscreen is one of Human-Machine Interface. It is an input device and normally layered on the top of an electronic visual display of an information processing system.
A user can give input or control the information processing system through simple or multi-touch gestures by touching the screen with a special stylus or one or more fingers.
The touchscreen enables the user to interact directly with what is displayed, rather than using a mouse, keyboard, or other such.
+ Resistive Touchscreen
+ Capacitive Touchscreen