RGB LEDs are widely used in many of the projects with Arduino platform. They work on the basic concept of combination of the basic colors of any shade, that is, red, green and blue. All the colors have these elementary color components in them. Thus, you can make any color we want using a RGB LED.
This is a 5mm RGB LED (Red Green Blue) with four pins. Triple output with a common cathode, this RGB LED can be used for three status indicators or pulse width modulates all three and gets mixed color.