Multithreading is becoming an increasingly important part of modern programming. One reason for this is that multithreading enables a program to make the best use of available CPU cycles, thus allowing very efficient programs to be written. Another reason is that multithreading is a natural choice for handling event-driven code, which is so common in today’s highly distributed, networked, GUI-based environments. Of course, the fact that the most widely used operating system, Windows, supports multithreading is also a factor. Whatever the reasons, the increased use of multithreading is changing the way that programmers think about the fundamental architecture of a program. Although C++ does not contain built-in support for multithreaded programs, it is right at home in this arena.