A 24bit RGB triple such as red (255,0,0) is often represented as a hex string because 16^2 = 256 and you only need 6 digits. Recall that the hex digits are (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F). So the color (255, 0, 0) would be (FF,0,0) or as a string FF0000. Usually people put a "#" at the front by convention to tag it as a hex. #FF0000. Alain Chesnais made me aware of a clever site that uses the fact that times are also 6 digits when seconds are included. For example 101236 is 36 seconds after 10:12. If one interprets that as a hex color, it is valid (note the maximum on 0..255 is 59 so they are all somewhat dark). There is a website that makes this more concrete so you can start internalizing hex codes. The dark ones anyway! Here's a screenshot.