Mucus alone isn't enough to diagnose disease, but it can give doctors useful insights into what's happening inside your body. After all, the stuff we blow out each day is a direct reflection of what our nasal cells are doing.
So to provide some insight into what the colour (and texture) of your snot says about your health, the Cleveland Clinic in the US has put together this handy infographic - apologies in advance for the US spelling. You can see a zoomable version here, and hopefully we don't need to tell you that an infographic can't replace the advice of a medical professional, but just in case, consider yourself warned.
Source: Cleveland Clinic