Coffee grains are green before they are roasted.
After the roasting they became brown. So this brown
gives the coffee that marvelous color. Each roaster
has a particular style. Same grain can be made from
the different roaster with a distinct taste.
Generaly there are 5 different ways to roast coffee;
LIGHT, AVERAGE, DARK, MORE DARKER, VERY DARK roasting...
These types change according to the usage of
coffee. Roasting figure out the grains marvelous
taste and flavour. And also the time and type of
the roasting is very important.

When roasting coffee coffee grains loose its weight
but it gains a volume. Market coffees are roasted
less not to loose its weight so much but this gives
thes kinds of coffees some kind of pepper
and sour taste.
LIGHT; Clear cinnamon color, a hazelnut taste,
high acidity. AVERAGE; Chestnut color,
caramel taste, high flavor. DARK; Dark brown color,
greasy apperance, like a chocalate taste.
MORE DARKER; Dark brown color, more greasy
apperance on the surface and sharp flavour.
VERY DARK; Black and very greasy, pepper
and sooty taste.