Glossary

Nginx

Nginx is a web server and reverse proxy with an asynchronous, event-driven architecture. Unlike Apache (one process per connection), Nginx handles thousands of connections in a single thread — consuming far less memory under peak load.

Nginx roles

Web server — serves static files (CSS, JS, images) directly, without PHP
Reverse proxy — accepts client requests and forwards them to PHP-FPM, Node.js, or another backend
Load balancer — distributes traffic across multiple servers
SSL termination — handles HTTPS so the backend can use plain HTTP internally

PHP + Nginx

Nginx cannot execute PHP itself. It forwards .php requests to PHP-FPM via the FastCGI protocol (fastcgi_pass). PHP-FPM processes the request and returns an HTML response.