The Fascia is the board that runs the length of the roof attached to the eave and faces outward. It is essentially the cap at the end of the eaves and rafters, and its bottom edge is attached to the soffit. It gives a surface for gutters to be attached to, and the board is either made up of vinyl or wood. Vinyl is more popularly used as wood is more prone to rotting with extended exposure to moisture. In cases where the roof edge is flush with the exterior walls you will often find vents in the fascia board. In other cases the venting is found in the soffit, under the eaves.
Fascia board can also be referred to as the trim board of a home, as it is often painted a complementary color to the siding of the house. Fascia board may require periodic repair or replacement as it is susceptible to water damage, and this can affect the rafters and other roofing materials as well.