Color coding refers to the practice of using different colors to distinguish, organize, or identify things. It helps make information or items easier to understand or find by assigning specific colors to different categories or purposes.
In the map, color codes for distance: purple dots are nearby galaxies; red dots are distant ones. (sciencemag.org)
Also, the sequel has numerous new features, including a customizable certificate of achievement, color coded on - screen keyboard, and customizable lesson plans. (gamesniped.com)