Overview
Nginx ("engine X") is a high-performance web server widely used as a reverse proxy, load balancer, and HTTP cache. Its event-driven architecture handles many concurrent connections with a small memory footprint, which is why it fronts a large share of the web's busiest sites.
Configuration model
Behavior is driven by nginx.conf plus included files. The key directives are server blocks (virtual hosts), listen (port), root (document root), and location (request routing). Always validate changes with nginx -t before reloading with nginx -s reload.
Ports and reloads
Nginx listens on port 80 by default on Linux (Homebrew uses 8080 so it can run without root). It reloads configuration without dropping connections via nginx -s reload.