What exactly module in D means?

[Francesco Cattoglio via Digitalmars-d-learn]

On Saturday, 5 July 2014 at 17:08:01 UTC, Olivier Pisano wrote:
> No, import is different from include. It does not stupidly copy
> and paste its content but tells the compiler to take the module
> into account for name resolution. The result may seem similar,
> but is much more efficient.

In fact, try to write the following C code:

int main() {
#include <stdio.h>
    [whatever else you want]
}

and look at those lovely error messages from the compiler :P