A house eave is the edge of the roof. In many instances, this edge extends beyond the house, which is what many people refer to as the eave. An eave has two parts: the fascia and the soffit.
The fascia is the part that runs along the house and covers up the rafters. The soffit is the paneling that lies over the fascia. An eave's function is to keep water from running down the sides of the house from the roof, which prevents leaks. Well placed eaves also help sunshine get through the windows in winter and provide shade for the house in summer, which can help with energy costs.