Recursion

**Recursion** in Data Structures and Algorithms (DSA) is a technique where a function calls itself to solve smaller instances of the same problem. It involves defining a base case to terminate the recursion and a recursive case that breaks down the problem into simpler subproblems. Recursion is crucial in algorithms like divide and conquer, backtracking, and dynamic programming. It's used in problems like tree traversals, depth-first search (DFS), the Fibonacci sequence, and the Tower of Hanoi. However, improper use of recursion can lead to stack overflow and inefficiency.