Hex color codes are Red-Green-Blue (RGB) color values coded in hexadecimal base. First group of two values represent red color value, second group of two values represent green color value, and the last group represents blue.
If you give zero for all six values, it shows as black, and if you give "F" (16 in hexadecimal) for all six values, it becomes white. So higher the value is, more light it has in it.
I hope you found this page on hex colour codes useful. Don't forget to share your favorite colours in the comments below!