I have a Borland compiler from about 2 years ago, and have only recently started learning C++. The book I have continually has the line using namespace std; at the top, and i don't know what it does. Whenever i include this line i get an error, so I take it out and it works fine. am i doing something wrong, or is my compiler too old to know what this means? does it really matter if I can't use the namespace feature at all?