Over the past three years PHP has evolved from a niche language used to add dynamic functionality to small sites to a powerful tool making strong breakthrough in large-scale, business-critical Web systems. Rapid maturation of PHP has created a skeptical population of users from more traditional language of "company" who question the readiness and ability of PHP to scale, as well as a large population of PHP developers without formal computer science backgrounds who have learned through hands-on experimentation while developing small and medium-sized applications in PHP. Although there are many books on learning PHP and developing small applications with it, there is a serious lack of information about the "scale" PHP for large-scale, business-critical systems.