A VPN is a more secure or private way of connecting to a remote server.

So, in SRS's case the remote server was the university, being accessed from home - or anywhere else. In Jon's case the remote server is his home, and is being accessed from elsewhere, and in both cases the objective is a secure encrypted connection.

In the case of a public VPN server, such as I think Mozilla is offering, the remote server is anywhere and it passes internet traffic to 'ordinary' servers - mudcat say. The objective is usually to hide that traffic from your ISP, or any other local snoopers. And maybe to pretend you're in the UK to watch iPlayer, say, in which case you choose a remote server in the UK.