\centerline{Spider User's Guide} This manual explains how to use the {Spider} program to generate a {\tt WEB} system for any programming language. It describes the syntax of the {Spider} description file used to describe a programming language, giving several examples. It does not say how to use the generated {\tt WEB} system; for that see ``The Spidery {\tt WEB} System of Structured Documentation.'' \bigskip \centerline{The Spidery {\tt WEB} System of Structured Documentation} This manual describes how to write programs in the {\tt WEB} language, using {\tt WEB} systems generated by {Spider}. Most of the material is taken verbatim from Donald Knuth's original memo introducing {\tt WEB}. It contains a brief introduction to the idea of literate programming, a short explanation of how to run {\tt WEAVE} and {\tt TANGLE}, and a list of all of the control sequences that can be used in {\tt WEB} programs and their effects.