31.4 Commands for Editing with Parentheses
This section describes the commands and features that take advantage
of the parenthesis structure in a program, or help you keep it
balanced.
When talking about these facilities, the term “parenthesis” also
includes braces, brackets, or whatever delimiters are defined to match
in pairs. The major mode controls which delimiters are significant,
through the syntax table (see Syntax). In Lisp, only parentheses
count; in C, these commands apply to braces and brackets too.
You can use M-x check-parens to find any unbalanced
parentheses and unbalanced string quotes in the buffer.