Nginx is an alternative to Apache for serving WordPress sites that provides better performance, scalability, and ability to proxy static files. It uses a non-blocking architecture that allows it to handle more requests with fewer system resources. Nginx may be a good choice for new server installs, sites where performance is critical, or as a front-end proxy. Its configuration involves setting up sites, includes, PHP fastcgi processing, and additional settings for multisite installations. Proper security practices should always be followed.