Why are we use the "using namespace std;" in the programm

Question

??

Answer 1

All your codes like"Cout << text " is actually "std::cout << text "
You can use namespace std so you will be able to omit the part "std::"

Answer 2

and the question is , why not trying to find out about it by removing that line ?
what I mean is , don't be afraid to try , you not gonna die just because you temporarily or even permanently remove codes..
unless you removed crucial line said Copyrights later on..