\appendix

Synopsis:

\appendix

This does not directly produce any output. But in a book or report it declares that subsequent \chapter commands start an appendix. In an article it does the same, for \section commands. It also resets the chapter and section counters to 0 in a book or report, and in an article resets the section and subsection counters.

In this book

\chapter{One}  ...
\chapter{Two}  ...
 ...
\appendix
\chapter{Three}  ...
\chapter{Four}  ...

the first two will generate output numbered ‘Chapter 1’ and ‘Chapter 2’. After the \appendix the numbering will be ‘Appendix A’ and ‘Appendix B’. See Larger book template, for another example.

The appendix package adds the command \appendixpage to put a separate ‘Appendices’ in the document body before the first appendix, and the command \addappheadtotoc to do the same in the table of contents. You can reset the name ‘Appendices’ with a command like \renewcommand{\appendixname}{Specification}, as well as a number of other features. See the documentation on CTAN.