C++ streams are relatively simple, easy to use, and very effective. If you look at the std::iostream class diagram, below, you will see the base class, std::ios, which composes std::streambuf or one of its derivative classes, and the stream classes.

• std::ios manages formatting and error data, and provides an interface into the streambuf classes.
• std::streambuf and its derivative classes manage the connection between a C++ program and the platform on which it runs.
• std::istream and std::ostream and their derivatives provide the most commonly used interfaces for program code to use the standard C++ streams.

• Input/Output Library - cppreference.com
• iostreams class diagram, ppt
• std::iostreams demo code
  • formatting
  • filebuf
  • file streams
  • stringstreams