Using namespace std vs std::

Question

I been reading some different books and some use using namespace std and others use std:: . Can someone explain the difference? Also to my understanding i think that syntaxes with std:: in front of it would lose that portion of it if i declare using namespace std. For example std::cout is the same as typing cout and declaring namespace in the beginning where the std:: portion is gone. Is my hypothesis about this correct? Thanks.

Answer 1

So i should just practice using std:: for good measure?

Answer 2

Thank you :)