Nginx

Nginx (pronounced "engine-x") is a high-performance HTTP server, reverse proxy, and load balancer that powers a significant portion of the internet. Originally created to solve the C10K problem (handling 10,000+ simultaneous connections), Nginx uses an event-driven, asynchronous architecture that handles massive concurrency with minimal memory usage.

In hosting environments, Nginx serves multiple roles. As a standalone web server, it serves static content extremely efficiently and handles PHP through FastCGI (php-fpm). As a reverse proxy, it sits in front of Apache or application servers, handling SSL termination, HTTP/2, caching, and connection management while passing dynamic requests to the backend.

The reverse proxy configuration is the most common deployment in hosting. Nginx handles all incoming connections, serves static files directly, and forwards dynamic requests to Apache or application servers. This setup combines Nginx's connection handling efficiency with Apache's .htaccess flexibility and module ecosystem.

Nginx also excels as a load balancer, distributing traffic across multiple backend servers with various algorithms (round-robin, least connections, IP hash). Health checks ensure traffic is only sent to responsive backends.

The open-source version covers most use cases. Nginx Plus (the commercial version) adds advanced load balancing, session persistence, active health checks, live dashboard, and dynamic reconfiguration via API. Most hosting providers run the open-source version with custom configurations tailored to their platform.