The purpose of this web site is to be an entry-level C programming language reference manual for personal computer software development with C18. This reference manual is not intended to be a comprehensive reference manual for the C standard. Only topics related to programming for personal computers is covered. The architectures covered are x86 and x86-64, as they are the most widely used in personal computing. The operating system covered is Linux, as it follows the C standard much closer than Microsoft Windows; the most widely used operating system for personal computing. The compiler covered is the GNU Compiler Collection (GNU C Library), as it is the most widely used compiler on Linux. Applying the information in this reference material to Microsoft Windows or another compiler and C standard library implementation should be trivial.