A knife sharpener is a tool designed to restore and maintain the sharp cutting edge of knives. Over time, regular use causes a knife’s edge to become dull due to friction, pressure, and microscopic damage to the metal. A knife sharpener works by grinding, honing, or polishing the blade’s edge to remove worn metal and reshape it into a fine, sharp edge. Knife sharpeners are commonly used in homes, professional kitchens, butcher shops, and outdoor settings such as camping or hunting.