Backer board is a type of building material commonly used in construction and renovation projects. It is typically made from cement, gypsum, or fiberboard and serves as a stable, moisture-resistant surface for tile installations, particularly in areas like bathrooms and kitchens. By providing a solid foundation, backer board helps prevent water damage and mold growth. In addition to its moisture-resistant properties, backer board is also lightweight and easy to cut, making it a popular choice among DIY enthusiasts and professionals alike. It is often installed over plywood or OSB (oriented strand board) to enhance the durability of the surface before applying tiles.