The Corruption is a hazardous surface biome that presents a dark purple "corrupted" theme. It may exist somewhere in a generated world, generally far from a player's original spawn point. It is the counterpart to the Crimson biome and its red bloody theme. A generated world will contain only one of the two, chosen at random during world creation, each with a 50% chance of occurring.
The two contain similar hazards, though each has its own unique enemies, items, and blocks. The tools, weapons, and armor obtained via Corruption materials are slightly less powerful than those obtained via Crimson materials, and Corruption enemies are also slightly less powerful.
The Corruption area that generates initially with the World is home to Chasms that lead to Shadow Orbs and Demon Altars. Corruption Chasms are especially hazardous to beginning players due to Fall Damage, and will have a tough or impossible time contending with them. Chasms are lined with Ebonstone, which can only be mined with a Copper Pickaxe/Nightmare Pickaxe/Deathbringer Picksaw or higher.