The Stanford GraphBase is a highly portable collection of programs and data for researchers who study combinatorial algorithms and data structures. All files are in the public domain and usable with only one restriction: They must not be changed! A ``change file'' mechanism allows local customization while the master files stay intact. The programs are intended to be interesting in themselves as examples of ``literate programming.'' Thus, the Stanford GraphBase can also be regarded as a collection of approximately 30 essays for programmers to enjoy reading, whether or not they are doing algorithmic research. The programs are written in CWEB, a combination of TeX and C that is easy to use by anyone who knows those languages and easy to read by anyone familiar with the rudiments of C.