title: What is a stream exactly?
body: <p>When my book says : a stream is a sequence of characters read or written from a device then my book says : the <code>istream</code> and the <code>ostream</code> types represent input and output stream ( what does it mean ?) how exactly do <code>cout</code> and <code>cin</code> work? </p>
  
  <p>I'm not a language native and I can't understand when my book says : the output operator writes the given value on the given <code>ostream</code>.</p>