A recurrence relation is a mathematical equation that defines a sequence of numbers where each term is expressed in terms of previous terms. This relationship allows us to compute the next term based on one or more preceding terms, making it a powerful tool in various fields such as computer science and mathematics. For example, the Fibonacci sequence is defined by a simple recurrence relation: each term is the sum of the two preceding terms. Recurrence relations can be used to model problems in algorithm analysis, dynamic programming, and combinatorics, providing a systematic way to solve complex problems.