How Does NGINX Web Server Work?


Scott Campbell

Web servers play a crucial role in delivering content from the internet to your device. NGINX is one such web server that has gained popularity due to its performance, scalability, and ease of use. In this article, we will dive into how NGINX works and why it has become a popular choice among developers and system administrators.

The Basics of NGINX

NGINX is an open-source web server that can also function as a reverse proxy, load balancer, and HTTP cache. It was created by Igor Sysoev in 2004 with the goal of solving the C10k problem – handling 10,000 concurrent connections efficiently. Over time, NGINX has evolved into a powerful tool used by many high-traffic websites around the world.

Understanding the Architecture

NGINX follows an event-driven architecture that allows it to handle a large number of concurrent connections without consuming excessive resources. It uses an asynchronous, non-blocking approach to handle requests efficiently.

Worker Processes: NGINX runs multiple worker processes to handle client requests. Each worker process can handle thousands of connections simultaneously.

Master Process: The master process manages all worker processes and coordinates their activities. It receives signals from the operating system and controls the lifecycle of worker processes.

Request Processing

The request processing in NGINX involves several stages:

  • Connection Handling: When a client makes a request to the server, NGINX accepts the connection and assigns it to an available worker process.
  • Read/Write Events: Once a connection is established, NGINX monitors read/write events on the socket without blocking other connections.
  • HTTP Module: NGINX’s HTTP module processes the incoming request. It parses the request headers, URI, and other details to determine how to handle the request.
  • Location Matching: NGINX uses location directives to match the incoming request’s URI against defined patterns.

    It then determines which configuration block to use for further processing.

  • Content Processing: NGINX performs various actions on the content, such as rewriting URLs, setting response headers, or caching static files.
  • Proxying and Load Balancing: NGINX can act as a reverse proxy and distribute incoming requests across multiple backend servers. This helps distribute the load and improve overall performance.
  • Caching: NGINX can cache responses from backend servers to reduce the load on those servers and improve response times for subsequent requests.
  • Error Handling: If any errors occur during processing, NGINX handles them appropriately and returns an error response to the client.

NGINX Configuration

The power of NGINX lies in its flexible and easy-to-understand configuration. The main configuration file is typically located at /etc/nginx/nginx.conf. It uses a simple syntax with directives that control various aspects of server behavior.

You can define server blocks that specify how NGINX should handle different domains or IP addresses. Within each server block, you can further define location blocks that determine how specific URIs should be processed.

A Simple Example

To illustrate this, consider the following example that sets up a basic server block:

    http {
        server {
            listen 80;
            location / {
                root /var/www/html;
                index index.html;

In this example, we define an HTTP server block that listens on port 80 for requests Targeting the domain The location block specifies that requests to the root URI (/) should be served from the /var/www/html directory, and the default file to serve is index.html.


NGINX’s popularity stems from its ability to handle high traffic loads efficiently while providing flexibility and scalability. Its event-driven architecture, along with features like reverse proxying, load balancing, and caching, make it a top choice for many web developers and system administrators.

By understanding how NGINX works under the hood and leveraging its powerful configuration options, you can build robust and performant web applications that can handle heavy traffic with ease.

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