title: What is the difference between using and include in c++?
body: <p>I know that include is for classes and using is for some built-in stuff, like namespace std... When you include something, you can create objects and play around with them, but when you are "using" something, then you can use some sort of built-in functions. But then how am I supposed to create my own "library" which I could "use"?</p>