31.4.3 Automatic Display Of Matching Parentheses
The Emacs parenthesis-matching feature is designed to show
automatically how parentheses (and other matching delimiters) match in
the text. Whenever you type a self-inserting character that is a
closing delimiter, the cursor moves momentarily to the location of the
matching opening delimiter, provided that is on the screen. If it is
not on the screen, Emacs displays some of the text near it in the echo
area. Either way, you can tell which grouping you are closing off.
If the opening delimiter and closing delimiter are mismatched—such
as in ‘[x)’—a warning message is displayed in the echo area.
Three variables control parenthesis match display:
blink-matching-paren turns the feature on or off:
disables it, but the default is
t to enable match display.
blink-matching-delay says how many seconds to leave the
cursor on the matching opening delimiter, before bringing it back to
the real location of point; the default is 1, but on some systems it
is useful to specify a fraction of a second.
blink-matching-paren-distance specifies how many characters
back to search to find the matching opening delimiter. If the match
is not found in that distance, scanning stops, and nothing is displayed.
This is to prevent the scan for the matching delimiter from wasting
lots of time when there is no match. The default is 25600.
Show Paren mode provides a more powerful kind of automatic matching.
Whenever point is after a closing delimiter, that delimiter and its
matching opening delimiter are both highlighted; otherwise, if point
is before an opening delimiter, the matching closing delimiter is
highlighted. (There is no need to highlight the opening delimiter in
that case, because the cursor appears on top of that character.) Use
the command M-x show-paren-mode to enable or disable this mode.
show-paren-mode uses colors to highlight the
parentheses. However, if your display doesn't support colors, you can
customize the faces
show-paren-mismatch-face to use other attributes, such as bold or
underline. See Face Customization.