PHP Links
PHP is one of the easiest languages to pick up, as a result many people have started off with it and learnt their way around. PHP has grown as the Linux and Apache web servers have grown in popularity. These days many websites use PHP and with PHP5 it is a better programming language than ever. The basic PHP itself is impressive, but then take all the extra add-ons that can be plugged in where needed and you have a powerful base on which to create your next web application.
PHP.net - the PHP homepage has the definitive PHP manual and glossary, explaing all the many built-in functions. See also Zend.
PHP Classes - examples of PHP scripts written by contributors to the site.
Pro Apache, Third Edition (Expert’s Voice) - excellent reading on the Apache web server.