changes.
@cindex active region
+@cindex activating the mark
Setting the mark at a position in the text also @dfn{activates} it.
When the mark is active, we say also that the region is active; Emacs
indicates its extent by highlighting the text within it, using the
@code{region} face (@pxref{Face Customization}).
+@cindex deactivating the mark
After certain non-motion commands, including any command that
changes the text in the buffer, Emacs automatically @dfn{deactivates}
the mark; this turns off the highlighting. You can also explicitly