From the official page,
nginx [engine x] is a HTTP and reverse proxy server, as well as a mail proxy server written by Igor Sysoev. It has been running for more than five years on many heavily loaded Russian sites including Rambler (RamblerMedia.com). According to Netcraft nginx served or proxied 4.70% busiest sites in April 2010. Here are some of success stories: FastMail.FM, WordPress.com.
W3Techs reports that 6.8% of the top 1 million sites on the web (according to Alexa) and 46.9% of top Russian sites use nginx. Netcraft reports similar 6.52% nginx share of the million busiest sites in April 2011.
Here are applications which Nginx can improve the performance.
- Ruby on Rails
- Movable Type
And also Nginx can improve many other application not listed here.
Here are languages which Nginx supports.
Nginx is known for its high performance, stability, rich feature set, simple configuration, and low resource consumption.
Taking advantage of the feature of Nginx, the number of users like world famous, high traffic and large scale web site is increasing.