What purpose do gargoyles serve in architecture?

Gargoyles primarily serve as water spouts designed to direct rainwater away from the sides of a building, particularly in Gothic architecture. By channeling water runoff from the roof, gargoyles help prevent erosion and damage to the building's walls and foundation. In addition to this functional aspect, they are often elaborately carved and serve as decorative features which add to the aesthetic appeal of the architecture. This combination of practicality and ornamentation is what makes gargoyles a distinctive and significant element in the design of historic structures. Hence, the answer accurately highlights both the functional and decorative roles that gargoyles fulfill in architectural design.