ginx is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server. Written by Igor Sysoev in 2005, Nginx now hosts between 1% and 4% of all domains worldwide (1, 2).

Nginx is known for its high performance, stability, rich feature set, simple configuration, and low resource consumption.

Nginx is one of a handful of servers written to address the C10K problem. Unlike traditional servers, Nginx doesn't rely on threads to handle requests. Instead it uses a much more scalable event-driven (asynchronous) architecture. This architecture uses small, but most importantly, predictable amounts of memory under load.
Even if you don't expect to handle thousands of simultaneous requests, you can still benefit from Nginx's high-performance and small memory footprint. Nginx scales in all directions: from the smallest VPS all the way up to clusters of servers.

At Daylife, we're running a whole lotta Python code inside Apache using mod_python. This works great so long as each request can be processed quickly, and you don't need your Python processes to keep much of anything in RAM.

However, any real web app inevitably needs to break those rules, at which point you start to venture into a world of increasing pain. Thus arises a need for alternatives to our cozy, familiar, tried-and-true mod_python.