Traditionally gable vents work to provide ventilation, releasing stagnant air, preventing damage from humidity, and optimizing temperature control. Gable vents are particularly useful during the summer months when hot air rises and is trapped in the attic, where it can transfer itself down through the ceiling and back into the level below, decreasing the effectiveness of air conditioning systems. A gable vent is located at the attic area, commonly on the exterior wall where the two planes of a sloping roof join, forming a triangle. The gable can be any symmetrical shape, but the triangle is among the most common. Other vent shapes include rectangles, steeples, circles, and octagons.