Recursion is the process of defining a problem (or the solution to a problem) in terms of (a simpler version of) itself. For example, we can define the operation "find your way home" as: If you are at home, stop moving. Take one step toward home.

Recursion is a technique used to solve computer problems by creating a function that calls itself until your program achieves the desired result.

Recursion is used to create loops in languages where other loops are not available. We use recursion only to implement mathematical formulas in code. Recursion is used to iterate through sequences of files and directories. Recursion lets us tackle complex problems by reducing the problem to a simpler one.

When writing a recursive function, you should think in a top-down manner. Do not worry about how the recursive call solves the sub-problem. Simply accept that it will solve it correctly.