What is Nginx?

What is Nginx?

Nginx is an open-source web server created in 2004 to solve the C10K problem — handling 10,000 concurrent connections efficiently. Where older servers like Apache spawned a new thread or process per request, Nginx uses an event-driven, non-blocking architecture that handles thousands of connections in a single thread.

This makes Nginx extremely fast and memory-efficient — exactly what you need in front of a production app.

Two Roles Nginx Plays

1. Web Server (Static File Server)

Nginx can serve static files (HTML, CSS, JS, images) directly from disk — fast, with no application code involved.

Request: GET /logo.png
Nginx reads the file from /var/www/html/logo.png and sends it directly.

This is how you'd serve a React build or a static site.

2. Reverse Proxy

A reverse proxy accepts requests from clients and forwards them to a backend server (your Node.js, Python, or any other app). The client never talks to your app directly.

Client → Nginx (port 80/443) → Node.js app (port 3000, localhost only)

Benefits of proxying through Nginx:

• Your app doesn't need to handle SSL
• Nginx can serve static files itself (fast), only sending dynamic requests to Node
• You can run multiple apps on one server, routing by domain name
• Nginx adds a layer of protection — your app's port isn't exposed to the internet

Nginx vs. Apache

	Nginx	Apache
Architecture	Event-driven, async	Thread/process-per-request
Concurrency	Excellent	Good
Memory usage	Low	Higher under load
Config style	Declarative blocks	Directive-based (.htaccess)
Static files	Very fast	Fast
Dynamic content	Proxies to app server	Can run PHP natively (mod_php)

For modern Node.js or Python backends, Nginx is the standard choice.

Configuration Structure

Nginx config lives at /etc/nginx/nginx.conf, but in practice you put site-specific config in /etc/nginx/sites-available/ and symlink it to /etc/nginx/sites-enabled/.

The core building block is the server block — equivalent to a virtual host:

server {
    listen 80;
    server_name example.com www.example.com;

    location / {
        proxy_pass http://localhost:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }
}

This configuration:

• Listens on port 80
• Accepts requests for example.com
• Forwards all traffic to a Node.js app on port 3000

Installing Nginx

On Ubuntu/Debian:

sudo apt update
sudo apt install nginx -y
sudo systemctl start nginx
sudo systemctl enable nginx   # start on boot

Verify it's running by visiting your server's IP in a browser — you should see the Nginx welcome page.

Key commands:

sudo nginx -t                  # test config for syntax errors
sudo systemctl reload nginx    # apply config changes without dropping connections
sudo systemctl restart nginx   # full restart
sudo tail -f /var/log/nginx/error.log   # watch error logs