Tile backer is a type of board used as a substrate for tile installations, particularly in areas exposed to moisture, like bathrooms and kitchens. It provides a stable, flat surface that helps prevent tiles from cracking and ensures a strong bond with adhesives. Common materials for tile backer include cement board, foam board, and fiber cement. Using tile backer is essential for protecting underlying structures from water damage. It acts as a barrier, preventing moisture from seeping into walls and floors. Proper installation of tile backer is crucial for the longevity and durability of the tile work.