What is a 'for loop' in programming?

A 'for loop' in programming is indeed a control flow statement that allows code to be executed repeatedly for a specific number of iterations, or based on a defined range of values. It is commonly used when the number of iterations is known beforehand, providing a compact and clear way to execute a block of code multiple times.

In a for loop, a counter or iterator is initialized, a condition is checked before each iteration, and the counter is updated after each iteration, which makes it efficient for tasks such as traversing through arrays or collections where the iteration count is determined based on their size.

The other options describe different programming concepts that do not pertain to the specific nature of a for loop. A 'for loop' does not serve as a data structure, nor is it explicitly a function or a method for defining variables. Rather, it acts as a mechanism to repeat operations, making it a fundamental part of control structures in programming.