Which concept refers to a function calling itself to solve a problem?

The concept that refers to a function calling itself to solve a problem is recursion. In programming, recursion is a technique whereby a function solves a problem by breaking it down into smaller instances of the same problem. This process continues until it reaches a base case, which is a condition that terminates the recursive calls.

For example, in calculating the factorial of a number, a recursive function would call itself with a decremented value until it reaches the factorial of zero, which is defined as one. This approach leverages the function's ability to simplify complex problems into manageable parts, making it a powerful tool in programming.

In contrast, iteration involves repeating a sequence of instructions until a certain condition is met, typically using loops. Inheritance refers to a fundamental concept in object-oriented programming where a class can inherit attributes and behaviors (methods) from another class. Encapsulation involves bundling the data and methods that operate on the data within a single unit, often a class, to control access and protect the integrity of the data. These concepts are important, but they do not involve the self-referential nature of recursion.