Nginx and reverse proxy

In short: A reverse proxy accepts requests from the internet and forwards them to one or more application servers. Nginx and Caddy are widely used programs for this.

In more detail: The proxy handles tasks in front of the application: TLS encryption, compression, caching, load distribution and protection against overload. The application behind it need not know any of that.

In Depth

• TLS termination: The proxy decrypts HTTPS; internally plain HTTP often runs.
• Static files: Nginx serves images, CSS and JS directly and very fast.
• Headers: The proxy sets headers such as X-Forwarded-For so the application knows the real client IP.
• Redirects and rewriting: Send old addresses to new ones.
• Counterpart: A forward proxy sits on the client side and forwards its requests to the internet.

See also: Load balancer, CDN (content delivery network)