What causes skin discloration like this?

i don't have this, but..i was wondering why other guys get discoloration on their beards like this


http://img293.imageshack.us/img293/3218/...

What causes skin discloration like this?
When you shave, you leave behind a minute amount of the hair at skin level. It appears that the skin is discoloured whereas what you are really seeing is the colour of the hair with skin in between.
Reply:It's hair. They call it the 5 o'clock shadow.