nginx

Nginx is an open-source software application that functions as an HTTP web server, reverse proxy, content cache, load balancer, TCP/UDP proxy server, and mail proxy server. Originally created by Igor Sysoev and released under the 2-clause BSD License, it is designed to handle high concurrency with low memory usage, making it a popular choice for serving static and dynamic content across the internet. As a web server, Nginx delivers static files (HTML, CSS, JavaScript, images) directly to clients with minimal overhead, and it can pass dynamic requests to application servers such as PHP-FPM, uWSGI, or Node.js via its reverse proxy capabilities. The reverse proxy functionality allows Nginx to sit between clients and backend servers, distributing incoming requests, caching responses to reduce load on upstream servers, and providing an additional layer of security by hiding internal server topology. In load balancing, Nginx supports several algorithms—round-robin, least connections, IP hash, and generic hash—to distribute traffic across multiple backend servers, improving reliability and throughput. Content caching is implemented through directives like `proxy_cache` and `fastcgi_cache`, enabling Nginx to store frequently accessed responses on disk or in memory, thus reducing response times and backend server strain. For TCP/UDP proxying, Nginx can forward non-HTTP traffic such as database connections (MySQL, PostgreSQL) or custom protocols, supporting SSL termination and health checks. The mail proxy module handles IMAP, POP3, and SMTP proxying with authentication and SSL offloading. Nginx's configuration system is declarative and event-driven: it uses a single configuration file (`nginx.conf`) with block directives (e.g., `http`, `server`, `location`) that allow fine-grain