What programming technique involves a function calling itself to solve a smaller instance of the same problem?

The concept of a function calling itself is known as recursion. This programming technique is particularly useful for solving problems that can be broken down into smaller, more manageable subproblems of the same type. In recursion, a function will typically have a base case that stops the recursion to prevent infinite loops and eventually simplifies the problem to where the solution is straightforward.

For example, a common use of recursion is in calculating factorials or traversing data structures like trees. When a recursive function is executed, it continues to call itself with modified arguments until it reaches the base case, at which point the stack of function calls starts to resolve itself, providing the desired result.

The other options do not describe this specific mechanism effectively. Iteration involves repeating a block of code until a condition is met, segmentation relates to breaking data into pieces for management or processing, and abstraction is about simplifying complexity by hiding details. None of these capture the essence of a function calling itself to address problems at varying scales, which is the hallmark of recursion.