# What Is Nginx: Architecture and Difference from Apache

> Explaining what Nginx is: master and worker processes, the event-driven model, and key differences from Apache in practice.

Nginx is a web server, reverse proxy, and load balancer in one program. It was created by Igor Sysoev in 2004 to solve the C10k problem: how to keep ten thousand simultaneous connections on one server without a performance collapse. Today Nginx serves a large share of internet traffic and runs on shared hosting, VDS, and dedicated servers, including the ZevsHost.net infrastructure.

## What Nginx is and why it exists

Nginx accepts HTTP requests from browsers and serves them files, pages, or forwards the request further to PHP-FPM, Node.js, or another backend. Besides static and dynamic content, it works as a reverse proxy, caches responses, encrypts traffic over SSL/TLS, and limits load from individual clients.

The main difference from a classic web server is that Nginx does not spawn a separate process or thread for every connection. This solves the core performance problem of older servers under a large number of simultaneous clients.

## How the Nginx architecture works: master and worker processes

Inside Nginx there is one master process and several worker processes. The master process starts as root, reads the configuration, opens sockets, and manages worker processes: it restarts them on failure and applies a new configuration without dropping connections.

Worker processes do all the real work: they accept connections, read requests, and send responses. Each worker is a single-threaded process, but thanks to the event-driven model, one worker handles thousands of connections in parallel. The number of worker processes is set by the worker\_processes directive and usually equals the number of CPU cores.

```
nginx -V
nginx -t
systemctl reload nginx
```

## Event-driven model instead of a process per connection

Apache in classic prefork mode spawns a separate process for every connection, and in worker mode a separate thread. As the number of clients grows, so does the number of processes, each consuming memory and requiring CPU context switches.

Nginx uses non-blocking I/O and the epoll system call on Linux (kqueue on BSD). A worker process does not wait for one operation to finish; instead it processes events from hundreds of connections in a loop. This is exactly what lets it hold 10,000 or more simultaneous connections on a modest VPS with 1-2 GB of memory.

## How Nginx differs from Apache

Apache is historically stronger at dynamic processing through modules like mod\_php, which embed the interpreter directly inside the web server. Nginx fundamentally does not embed interpreters: it hands dynamic content off over FastCGI to PHP-FPM or over HTTP to an upstream server. This pairing is covered in detail in the article on [Nginx and PHP-FPM](https://www.zevshost.net/en/kb/nginx-php-fpm-svyazka/).

Another difference is the configuration file. Apache uses .htaccess in every site folder, which the server rereads on every request. Nginx configuration is static: .htaccess is not supported at all, and rules are described in a server block, covered in detail in the article on [Nginx virtual hosts](https://www.zevshost.net/en/kb/nginx-server-block-virtualnye-hosty/).

## Comparison table: Nginx versus Apache

| Parameter | Nginx | Apache |
| --- | --- | --- |
| Processing model | Event-driven, one worker for thousands of connections | Process/thread per connection |
| .htaccess support | No | Yes |
| PHP handling | Via FastCGI and PHP-FPM | Built-in mod\_php module |
| Memory use under growing load | Grows slowly | Grows proportionally to connection count |

## Where Nginx is used in practice

Typical use cases for Nginx on servers and hosting accounts:

- Web server for static content: HTML, CSS, JS, images without any backend.
- Reverse proxy in front of PHP-FPM, Node.js, or a Java application.
- Load balancer distributing traffic across several backend servers.
- TLS terminator: handling HTTPS in front of internal services over HTTP.
- Caching layer in front of a slow origin server.

## Where to start configuring Nginx

Before writing location rules and setting up proxying, you need to install the server itself and understand its configuration file structure. The order is:

1. Install the Nginx package from the official repository, as described in the article on [installing Nginx on Ubuntu and Debian](https://www.zevshost.net/en/kb/nginx-ustanovka-ubuntu-debian/).
2. Study the configuration structure and create the first server block for your domain.
3. Set up dynamic content handling through PHP-FPM or a reverse proxy to the required backend.
4. If the site is moving from an old server, check the article on [migrating from Apache to Nginx](https://www.zevshost.net/en/kb/migratsia-apache-na-nginx/) so you do not lose rules from .htaccess.

Nginx beats Apache on memory consumption and on the number of simultaneous connections on equal hardware, but it requires a different approach to configuration: no .htaccess and no built-in PHP interpreter. That trade-off pays off on loaded sites and on VPS instances with limited resources.

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Source: https://www.zevshost.net/en/kb/nginx-chto-takoe-arhitektura/