Gable vent
A vent in the upper exterior wall that lets hot attic air escape.
A gable vent is the louvered opening you often see in the triangular upper section of an exterior wall. Along with soffit and ridge vents, it's part of how an attic breathes — letting hot, moist air out so the space doesn't bake your roof shingles or grow mold in winter. Keep the louvers and their screens clear, and make sure insulation isn't blocking airflow from the soffits.