In just a few years PHP has rapidly evolved from a small niche language to a powerful web development tool. Now in use on over 14 million Web sites, PHP is more stable and extensible than ever. However, there is no documentation on how to extend PHP; developers seeking to build PHP extensions and increase the performance and functionality of their PHP applications are left to word of mouth and muddling through PHP internals without systematic, helpful guidance. Although the basics of extension writing are fairly easy to grasp, the more advanced features have a tougher learning curve that can be very difficult to overcome. This is common at any moderate to high-traffic site, forcing the company hire talented, and high-priced, developers to increase performance. With Extending and Embedding PHP, Sara Golemon makes writing extensions within the grasp of every PHP developer, while guiding the reader through the tricky internals of PHP.