What is the meaning of using namespace in iostream library??

Question

Using namespace std;

Answer 1

Using namespace std
Std means "standard". When you want to use terms like cin and cout, it would be easier if you put "using namespace std" at the beginning and you can use it as usual.
Else, whenever you want to use cin and cout,you have to write it this way : std::cin and std::cout.
You can try refering here : https://stackoverflow.com/questions/18914106/what-is-the-use-of-using-namespace-std