Multi-coating refers to the application of multiple layers of optical coatings on lenses or other surfaces to enhance their performance. These coatings can reduce reflections, improve light transmission, and minimize glare, making them particularly useful in products like glasses, camera lenses, and binoculars. The process involves layering different materials, each designed to target specific wavelengths of light. By carefully controlling the thickness and composition of these layers, manufacturers can achieve desired optical properties, resulting in clearer images and better visual experiences for users. Multi-coating is essential in high-quality optics, ensuring optimal functionality and durability.