Invariants are properties or conditions that remain unchanged throughout a process or operation. In computer science, they are often used in algorithms and data structures to ensure that certain conditions hold true at specific points in execution. For example, in a sorting algorithm, an invariant might be that the elements before a certain index are always sorted. In mathematics, invariants can refer to quantities that do not change under transformations, such as geometric transformations or algebraic operations. For instance, the area of a shape remains invariant when it is rotated or translated. Understanding invariants helps in analyzing and proving the correctness of various systems and processes.