Some Emacs packages are mentioned here as an aid to the new Viper user, to indicate what Viper is capable of. A vast number comes with the standard Emacs distribution, and many more exist on the net and on the archives.
This manual also mentions some Emacs features a new user should know about. The details of these are found in the GNU Emacs Manual.
The features first. For details, look up the Emacs Manual.
Makes and Compiles can be done from the editor. Error messages will be parsed and you can move to the error lines.
You can talk to Shells from inside the editor. Your entire shell session can be treated as a file.
Mail can be read from and sent within the editor. Several sophisticated packages exist.
Editing modes are written for most computer languages in existence. By controlling indentation, they catch punctuation errors.
The packages, below, represents a drop in the sea of special-purpose packages that come with standard distribution of Emacs.
ange-ftp.el can ftp from the editor to files on other machines
transparent to the user.
vc.el for doing RCS commands from inside the editor
dired.el for editing contents of directories and for navigating in
the file system.
font-lock.el for automatic highlighting various parts of a buffer
using different fonts and colors.
desktop.el for saving/restoring configuration on Emacs exit/startup.
ispell.el for spell checking the buffer, words, regions, etc.
ediff.el for finding differences between files and for applying
Emacs Lisp archives exist on ‘archive.cis.ohio-state.edu’ and ‘wuarchive.wustl.edu’