NGINX (pronounced "Engine-X") is a high-performance, open-source software that handles the heavy lifting of modern web traffic. Originally created in 2004 to solve the "C10k problem" (handling 10,000 concurrent connections at once), it has become the standard for high-speed infrastructure.Nginx is often called a "Swiss Army Knife" for DevOps because it performs four main roles: Web Server: It delivers static content (HTML, CSS, images) much faster and with less memory than older servers like Apache. Reverse Proxy: It sits in front of your application (like a Node.js or Python app) to manage requests, providing an extra layer of security and abstraction. Load Balancer: It distributes incoming traffic across multiple backend servers to ensure no single server gets overwhelmed. API Gateway: It manages and routes API requests, handling authentication and rate limiting.