Dark roast coffee is made by roasting the beans until they begin to smoke — giving them a deep brown color and bold, smoky flavor. This level of roast causes the sugars contained inside the beans to fully caramelize.
Medium-roast coffee is removed right as the beans start to pop (second crack), producing a lighter, more balanced flavor.
Light roast coffee is removed as soon as the beans begin to brown — the flavors are brighter and more acidic.