If you know anything about Web servers, you know that open-source Apache is the number one Web server in the world by a wide margin. You also know that Microsoft’s Internet Information Services (IIS) is the number two Web server. As of the end of 2011, though, you’d also be wrong about second place. The number two active Web server, according to Netcraft, the leading Web server analytics company, is now NGINX.
NGINX, pronounced Engine-X, if you don’t know it, is an open-source Web and reverse proxy server and e-mail proxy server to boot. It’s has been used for years on many popular Russian Web sites such as Yandex, Vkontakte, and Rambler. In recent years, it’s been picked up by major Western sites including Facebook and WordPress.com.
These Web sites, and millions of others, have moved to NGINX because it’s very fast and uses few system resources. The company has claimed that NGINX can deliver 10 times the performance of the leading Web server on the same hardware. I’m not sure about that but I do know it’s faster than Apache or IIS. NGINX manages this by being event-based. So, it doesn’t spawn new processes or threads for each Web page request. That means that even as the Web server load increases, memory use remains low and predictable.