htmlentities Convert all applicable characters to HTML entities stringhtmlentities stringstring intquote_style stringcharset This function is identical to htmlspecialchars in all ways, except with htmlentities, all characters which have HTML character entity equivalents are translated into these entities. Like htmlspecialchars, the optional second quote_style parameter lets you define what will be done with 'single' and "double" quotes. It takes on one of three constants with the default being ENT_COMPAT: Constant Name Description ENT_COMPAT Will convert double-quotes and leave single-quotes alone. ENT_QUOTES Will convert both double and single quotes. ENT_NOQUOTES Will leave both double and single quotes unconverted. Support for the optional quote parameter was added in PHP 4.0.3. Like htmlspecialchars, it takes an optional third argument charset which defines character set used in conversion. Support for this argument was added in PHP 4.1.0. Presently, the ISO-8859-1 character set is used as the default. &reference.strings.charsets; If you're wanting to decode instead (the reverse) you can use html_entity_decode. bold"; // Outputs: A 'quote' is <b>bold</b> echo htmlentities($str); // Outputs: A 'quote' is <b>bold</b> echo htmlentities($str, ENT_QUOTES); ?> ]]> See also html_entity_decode, get_html_translation_table, htmlspecialchars, nl2br, and urlencode.