In the installation chapters of this book, you have the option of installing PHP 4.3.x or PHP 5.x, as PHP 5.x is now an official customer release, albeit in its infancy. All PHP-related elements in this book are relevant for both the 4 and 5 release families, so your decision will not affect your ability to learn the processes in this book.
During the last few years, the PHP Group and the developers at Zend Technologies were simultaneously working on the next generation of PHP, version 5. Given how full-featured PHP has become since its inception, it's difficult to imagine what the next generation could possibly contain. In this short chapter, you'll learn about the new features in PHP 5, including