using std namespace; what does it mean? - Dev Shed

using std namespace; what does it mean? - Dev Shed
Without namespace

Code:

#include 

int main () {
 std::cout << "Hello world!\n";
 return 0;
}

With namespace

Code:

#include 
using namespace std;

int main () {
 cout << "Hello world!\n";
 return 0;
}