Engine what? Nginx (engine-x) is a web server and reverse proxy for web and mail protocols (HTTP, HTTPS, SMTP, POP3 and IMAP). It has been first released in 2004, and its usage keeps growing ever since (according to Netcraft, it was hosting 14.47% of active sites in August 2014). It’s capable of hosting many kinds of applications: static HTML pages PHP, using PHP-FPM Ruby on Rails and any kind of Rack-based Ruby application, using Phusion Passenger proxying requests to another webserver (e.g. a software launching its own web server, like Kodi)