This chapter is an introduction to system programming, exploring a range of topics from its original definition to how it has shifted in time with system evolution. This chapter provides some basic concepts and an overview of Unix and its resources, including the kernel and the application programming interfaces (API). Many of these concepts are defined here and are used in the rest of the book.

The following topics will be covered in this chapter:

• What is system programming?
• Application programming interfaces
• Understanding how the protection ring works
• An overview of system calls
• The POSIX standard