C is a standard. It is the programmers programming language. It is the standard programming language of GNU and BSD based systems. The majority of these systems and the applications that run on them, is written in C. C was developed over thirty years ago for writing operating systems and applications. It's small, extensible design has allowed it to evolve with the computer industry. Because of it's age and popularity, C is a very well supported language. Many tools exist to make C programming easier and these tools are often very mature and of a high standard. All the software we will use in this book is written in C.