A slat is a narrow, flat piece that is usually found in blinds or shutters, serving the purpose of regulating light and air. It can be either horizontal or vertical. Louver, however, is a set of slats organized to enable airflow, featuring slats that can be tilted to manage the direction and volume of air circulation. Unlike slats which are individual parts, louvers are entire systems created for controlling air and light, typically seen on windows, vents, or outdoor structures.