This is a major mode intended for editing Apache HTTPD configuration files. It provides syntax colouring to identify sections and keywords, to catch misspellings, and to look nice. It works either with GNU Emacs or with XEmacs/SXEmacs.
If you are reading this file offline then the master source code repository can be found at: https://github.com/martenjj/apachemode
If the mode is not included as standard with your Linux distro or Emacs installation, then you can download it from here and install it yourself. Clone the Git tree or download a tarball, go into the 'apachemode' directory and simply do 'make' to generate the Lisp files.
Emacs only needs the two generated .el files (apache-mode-el and apache-mode-autoload.el); look near the end of apache-mode.el or see the docstring of apache-set-file-patterns within Emacs to see how to get them loaded.
This mode was originally written in 1999, long before the advent of online repositories such as GitHub. Since then a number of people and distribution channels have taken it and improved and extended it in various ways - see the Git history for more information and credits. This is completely within the spirit of open source software and there's nothing nothing wrong with that at all, but it means that there are a number of different versions being distributed and available for download but all with slightly different features and implementations.
This repository on GitHub is an attempt to bring all of those different versions together again. I have tried to combine the best features of each available version and to ensure that it is up-to-date. Further development is encouraged, so if you have any suggestions or improvements then please report issues or make a pull request here.