Varnish (Vinyl) HTTP Accelerator

Varnish is a high performance caching reverse proxy, a software package that operates as a caching server.  It runs as a daemon service like any other long running background process.

systemctl start varnish
 systemctl stop varnish
 systemctl status varnish
```
- It starts automatically on boot (if configured to)
- It runs continuously, listening on a port (typically **port 80 or 6081**)

## Good analogy to MySQL

| | MySQL | Varnish |
|---|---|---|
| **Type** | Daemon/service | Daemon/service |
| **Managed by** | systemd | systemd |
| **Listens on** | Port 3306 | Port 80/6081 |
| **Sits in front of** | Your app | Your web server |
| **Purpose** | Store data | Cache HTTP responses |

So yes — mentally it's the same kind of thing as MySQL. It's software running as a service on a server.

## Is it a physical computer?

No — Varnish is just **software**. It runs on:
- A bare metal server
- A VM
- A container (Docker)
- The same machine as your web server (less ideal) or a dedicated machine in front of it

## Typical real-world setup
```
Internet → [Server A: Varnish] → [Server B: Nginx/Apache + Your App]