This document discusses best practices for building scalable PHP websites, as demonstrated by ZingMe's architecture. It covers scaling by adding servers horizontally (scaling out) rather than vertically on single servers. Key aspects covered include load balancing with HAProxy, managing user sessions in Memcached to allow scaling, and deploying code changes automatically across servers using SVN and scripts. ZingMe's implementation supports over 1.7 million daily active users on over 300 servers through these scalability techniques.