An "injective" function, also known as a one-to-one function, is a type of mapping between two sets where each element in the first set is paired with a unique element in the second set. This means that no two different elements in the first set can map to the same element in the second set. For example, if you have a function that assigns students to their unique student IDs, it is injective because each student has a distinct ID. In mathematical terms, a function f: A \to B is injective if for every pair of elements a_1 and a_2 in set A, if f(a_1) = f(a_2) , then it must be true that a_1 = a_2 . This property is important in various fields, including mathematics, computer science, and data analysis, as it ensures that information is preserved without duplication.