Kryptonite is a fictional mineral from the DC Comics universe, primarily known as the weakness of the superhero Superman. It is often depicted as a glowing green rock that emits radiation harmful to Kryptonians, the race to which Superman belongs. When exposed to Kryptonite, Superman experiences physical pain and weakness, making it a significant threat to him. The concept of Kryptonite first appeared in the 1940s and has since evolved to include various colors, each with different effects. For example, red Kryptonite can cause unpredictable changes in Superman's behavior, while gold Kryptonite can permanently remove his powers.