Like most systems administrators of the day I learnt vi and used it extensively. Unlike Emacs, vi was standard text editor across many Unix platforms. However times have changed Emacs is now available almost everywhere and also that I have now moved away from system administration towards academics I find myself using emacs more often.
Whenever you save a file, emacs copies the current version to file with same name followed by a tilde(~). Its a good idea to allow emacs to back up files like this since you can revert back to older version of the edited files easily. However this not a good idea when editing files say on publicly accessible remote web server. Since I use AngeFtp to retrieve and edit file in emacs I set ange-ftp to disable backup files in my ~/.emacs file.
(setq ange-ftp-make-backup-files nil)