Nginx is an Open Source web server that can also be used as a reverse proxy, load balancer, mail proxy, and HTTP cache used on over 400 million websites.

Nginx basic Features:

Serving static and index files, autoindexing, open file descriptor cache
Accelerated reverse proxying with caching, load balancing, and fault tolerance
Accelerated support with caching of FastCGI, uwsgi, SCGI, and Memcached servers; load balancing and fault tolerance
Modular architecture. Filters include gzipping, byte ranges, chunked responses, XSLT, SSI, and image transformation filters. Multiple SSI inclusions within a single page can be processed in parallel if they are handled by proxied or FastCGI/uwsgi/SCGI servers
SSL and TLS SNI support
Support for HTTP/2 with weighted and dependency-based prioritization

Those new to Nginx can find Online Documentation here

Notes for Windows users:

The version of Nginx for Windows uses the native Win32 API (not the Cygwin emulation layer). Only the select() connection processing method is currently used, so high performance and scalability should not be expected. Due to this and some other known issues, this version of Nginx for Windows is considered a beta version. At this time, it provides almost the same functionality as a UNIX version of NGINX except for the XSLT filter, image filter, GeoIP module, and embedded Perl language.

To install Nginx/Windows, download the latest mainline version distribution (1.1x.x) since the mainline branch of NGINX contains all known fixes. Then unpack the distribution, go to the Nginx-1.1x.x directory, and run Nginx. Here is an example for the drive C: root directory:

cd c:\
unzip Nginx-1.1x.x.zip
cd Nginx-1.1x.x
start Nginx