A fabric whitener is a laundry product specially designed to make white clothes look brighter, cleaner, and whiter. It works by removing dullness, yellow stains, and greying caused by repeated washing, sweat, and dirt. Many whiteners also contain optical brighteners that enhance the brightness of fabrics and give them a fresh, new appearance. Fabric whiteners can be used with regular detergent during washing or as a final rinse solution. They are suitable for clothes like shirts, uniforms, bedsheets, towels, and cotton garments.