Grout repair involves fixing damaged or discolored grout lines between tiles. Over time, grout can crack, crumble, or stain due to moisture, dirt, or wear. Repairing grout helps maintain the appearance of tiled surfaces and prevents water damage to the underlying structure. The repair process typically includes cleaning the existing grout, applying a new grout mixture, and sealing it to protect against future issues. Tools like a grout float, grout saw, and caulk gun may be used. Regular maintenance can extend the life of grout and keep tiled areas looking fresh and clean.