If you are a new user to emacs, you may have noticed that the 
backspace key doesn't do what you would expect it to - in particular,
it invokes emac's help command.  This is because the backspace key
generates a "control-H" character, and by default emacs mnemonically
maps this key to invoke help.

A common solution to the problem is to redefine the backspace key to 
actually do a destructive backspace, and to remap the key sequence for
the help command, usually to the two key sequence "control-x ?".

To make emacs behave this way for you, place the following two lines
in a file in your home directory called ".emacs".   Then every time
you invoke emacs backspace (control-H) will do what you expect, and you'll
still be able to access the help system by typing "control-x ?":

(define-key global-map "\C-x?" 'help-command)
(define-key global-map "\C-h" 'backward-delete-char-untabify)