This is a color picker for Minecraft! In Minecraft, color codes are generated using a specific math formula. This does that for you! You can use it for custom leather armor colors, firework colors, etc.
If you want to know the formula for changing RGB color to Minecraft usable codes, it is blue + 256 * green + 65536 * red. Pretty simple, but hey, why do that work when this can do it for you?