Kryptonite is a fictional material that appears primarily in Superman stories published by DC Comics. In its best-known form, it is a green, crystalline material originating from Superman’s home world of Krypton. It emits a unique, poisonous radiation that can weaken and kill Kryptonians.

It was first introduced in the radio serial The Adventures of Superman in 1943 and later in the comics in 1949. It was initially a plot device to create a weakness for Superman, who was otherwise invulnerable and unstoppable. It also served as a way to explore Superman’s origin and connection to his lost planet.

Why it affects Superman?

It weakens Superman because it interferes with his ability to absorb and process solar energy from Earth’s yellow sun, which is the source of his powers. Its radiation blocks or disrupts the solar radiation in his cells, causing him to lose strength, speed, durability, senses, and other abilities. It also causes him pain, nausea, fever, and death if exposed to it for too long.

It has been weaponized to attack Superman and Supergirl by enemies such as Lex Luthor, Metallo, Brainiac, Bizarro, and Darkseid. They have used it in multiple forms, such as bullets, knives, rings, bombs, lasers, gas, dust, or synthetic. 

Colors of Kryptonite.

They have also used different colors of kryptonite, which have other but generally adverse effects on Kryptonians. For example:

• Red kryptonite alters the personality or behavior of Kryptonians in unpredictable ways, such as making them evil, reckless, paranoid, or amnesiac.
• Gold kryptonite permanently removes the powers of Kryptonians by destroying their ability to absorb solar energy.
• Blue kryptonite affects Bizarro and other imperfect clones of Superman in the same way green kryptonite affects Superman.
• Black kryptonite splits Kryptonians into two separate beings: good and evil.
• White kryptonite kills all plant life from Krypton or Earth.
• Pink kryptonite makes Kryptonians gay or bisexual.

Conclusion

It is one of the Superman mythos’ most iconic and recognizable elements. It is also a metaphor for a great exploitable weakness or vulnerability that can bring down even the most potent or heroic person.