A bijective function is a type of function that establishes a one-to-one correspondence between elements of two sets. This means that every element in the first set is paired with exactly one unique element in the second set, and vice versa. In simpler terms, a bijective function ensures that no two elements from the first set map to the same element in the second set, making it both injective (one-to-one) and surjective (onto). Bijective functions are important in various fields, including mathematics, computer science, and cryptography. They allow for the creation of invertible functions, meaning that you can reverse the mapping to retrieve the original input. This property is essential for solving equations and understanding relationships between different sets.