This chapter introduced enough of C++ to let the reader compile and execute simple C++ programs. We saw how to define a main function, which is the function that is executed first in any C++ program. We also saw how to define variables, how to do input and output, and how to write if, for, and while statements. The chapter closed by introducing the most fundamental facility in C++: the class. In this chapter we saw how to create and use objects of a given class. Later chapters show how to define our own classes.