What is the user@host?

This might be a stupid question but

```
Copy them to keys folder: 
- From host: $ cp ~/.ssh/id_rsa.pub ~/git-server/keys
- From remote: $ scp ~/.ssh/id_rsa.pub user@host:~/git-server/keys
You need restart the container when keys are updated:
$ docker restart <container-id>
```

What is the user@host here?  I'm guessing it relates to the localhost? and the hostname?

Thanks,
 