abbrev

abbreviation handling, typing shortcuts, macros.

bib

code related to the bib bibliography processor.

c

support for the C language and related languages.

calendar

calendar and time management support.

comm

communications, networking, remote access to files.

convenience

convenience features for faster editing.

data

support for editing files of data.

docs

support for Emacs documentation.

emulations

emulations of other editors.

extensions

Emacs Lisp language extensions.

faces

support for multiple fonts.

files

support for editing and manipulating files.

frames

support for Emacs frames and window systems.

games

games, jokes and amusements.

hardware

support for interfacing with exotic hardware.

help

support for on-line help systems.

hypermedia

support for links between text or other media types.

i18n

internationalization and alternate character-set support.

internal

code for Emacs internals, build process, defaults.

languages

specialized modes for editing programming languages.

lisp

Lisp support, including Emacs Lisp.

local

code local to your site.

maint

maintenance aids for the Emacs development group.

mail

modes for electronic-mail handling.

matching

various sorts of searching and matching.

mouse

mouse support.

multimedia

images and sound support.

news

support for netnews reading and posting.

oop

support for object-oriented programming.

outlines

support for hierarchical outlining.

processes

process, subshell, compilation, and job control support.

terminals

support for terminal types.

tex

supporting code for the TeX formatter.

tools

programming tools.

unix

front-ends/assistants for, or emulators of, UNIX-like features.

wp

word processing.