Raw denim is made of authentic, unwashed denim. They always come in dark indigo color, and fit really really tight when you first put em on (you're supposed to buy 1-2 waist sizes smaller than you would with regular denim). Then, you wear them for 6-8 months without washing them.
The unique properties of the raw denim will stretch to fit your physique, and when you wash them after the first 6-8months the dye will wash out of the creases and create a cool fade/whiskering pattern unique to you. Basically, as you wear them the jeans become an expression of you, they're pretty sick. Here's a good example
I only ever had one pair, and when I started working out my legs quickly outgrew them but if my memory serves most popular pairs are some form of skinny cut. Check out APC's "new standard," it pretty much is the standard (go figure) in the field of raw denim.