What term describes a function that calls itself either directly or indirectly?

A function that calls itself either directly or indirectly is referred to as a recursive function. Recursion is a fundamental concept in programming and algorithms, where a function solves a problem by breaking it down into smaller instances of the same problem. When a recursive function is defined, it usually consists of a base case that provides a stopping condition, and a recursive case that allows the function to continue calling itself with modified parameters.

This technique is particularly useful for tasks such as calculating factorials, traversing data structures like trees, and implementing algorithms that benefit from a divide-and-conquer approach. The nature of recursion can lead to elegant solutions that are often simpler and more understandable compared to their iterative counterparts.

In contrast, an iterative function typically uses explicit loops to achieve repetition and does not involve self-calling. Anonymous functions are defined without a name and are primarily used for short-lived tasks, while static functions are not inherently related to recursion; they are usually tied to a particular class or module and do not retain state between calls.