Answer 1

The concept is pretty straightforward ¹. for example, in case of using `static` in the context of `static Vs. dynamic variables`, a static variable's life lasts till the whole program gets terminated.

void f() {
int a = 10;
static int b = 20;

printf("a: %d, b: %d\n", ++a, ++b);
}

int main() {
f();
f();
f();
}

Output:
a: 11, b: 21
a: 11, b: 22
a: 11, b: 23

The lifetime (NOT scope) of `static int b` won't end when leaving f()'s body but with the whole program. So, it keeps the previous value on the next call.

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¹ https://en.wikipedia.org/wiki/Static_variable