What do you mean by color code?

A color code is a system for displaying information by using different colors. The earliest examples of color codes in use are for long-distance communication by use of flags, as in semaphore communication. How does color code work? Hex color codes start with a pound sign or hashtag (#) and are followed by six letters and/or numbers. The first two letters/numbers refer to red, the next two refer to green, and the last two refer to blue. ... Numbers are used when the value is 1-9. Letters are used when the value is higher than 9