c++ - Using std Namespace

There seem to be different views on using 'using' with respect to the std namespace.

Some say use ' using namespace std', other say don't but rather prefix std functions that are to be used with ' std::' whilst others say use something like this:

using std::string;
using std::cout;
using std::cin;
using std::endl;
using std::vector;

for all the std functions that are to be used.

What are the pros and cons of each?