The most relevant website probably is http://www.php.net/ and the online manual at http://www.php.net/manual/en/. The PHP home page presents the latest developments in the PHP world, whereas the manual contains up-to-date information about functions, enriched by user comments that help to solve one problem or two. http://www.php.net/links.php lists more than 100 websites related to PHP, so this is a perfect starting point for interesting information. However, in this appendix we mention those websites we deem important or that we personally visit regularly. Your mileage may vary.