Q:

how to delete region with [delete] key in emacs

I am using Emacs 23.3 on Mac OS X Lion. How can I delete the selected text region with simple key typing—something like delete or C-d? This works on windows without setting anything specific. How can I implement that in Mac OS X Lion?

A:

You need to enable delete-selection-mode and then it will work ;-)

A:

Try M-xcua-mode. This will change a lot of things about the way Emacs behaves to fit the behavior of other GUI applications. For more information, see M-S-:(info "(emacs) CUA Bindings").
You can turn it on persistently with M-xcustomize-optionRETcua-mode.

A:

If you mean "delete between the mark and the cursor," the normal keybinding for this in Emacs is C-w (Hold down control and press w).
To set the mark, use C-SPC (hold down control and press SPACE).
Selecting a text region and then deleting it is not very common to normal Emacs users. More frequently they use 

C-k to delete entire lines at a time (or to the end of the current line)
M-z (press Esc then z) to "zap to char" which will delete all text to the next occurrence of any character
M-DEL (press Esc then DEL) to delete backwards a whole word at a time

and others.

