How exactly does tail recursion work?

Question

I almost understand how tail recursion works and the difference between it and a normal recursion. I only don\'t understand why it doesn\'t

Answer 1

The compiler is simply able to transform this

int fac_times (int n, int acc) {
    if (n == 0) return acc;
    else return fac_times(n - 1, acc * n);
}

into something like this:

int fac_times (int n, int acc) {
label:
    if (n == 0) return acc;
    acc *= n--;
    goto label;
}