Recursion is a process where a function calls itself. In C, functions can call themselves recursively. As an example, calculating the factorial of a number recursively is described. Factorial of a number n is defined as n * (n-1) * (n-2) ... * 1. The recursive factorial function calls itself with decreasing arguments until it reaches 1, at which point it returns 1. It then multiplies the returned values together up the call stack to calculate the final factorial value. Visualizing the recursive calls is difficult, but it is drawn out step-by-step in the document as an example for calculating 3!. Though recursion may seem complex, it can often be the most direct way to code certain algorithms