The first course of shingles installed on your roof. It will be under the first exposed row. Often these shingles are 20 year three tab shingles. So as to not create an awkward hump, these are used even when heavier laminated shingles are installed.

The first course of roofing materials installed along the downslope perimeter edge. The starter course is usually covered by the first course of roofing.

The primary course of roofing materials. The Starter course is installed along the roof eave and is usually covered by the first course of roofing.