Tarnished, or dull, refers to the loss of luster and shine on metal surfaces, often caused by oxidation or exposure to moisture. This process can affect various metals, including silver, copper, and brass, leading to a gray or brown film that diminishes their appearance. The tarnishing process is a natural chemical reaction that occurs over time, especially in humid environments. While it can be removed through cleaning methods, such as polishing or using specific solutions, prevention strategies like proper storage and regular maintenance can help keep metals looking bright and new.