Q:

Can somebody clarify the Tor --> VPN and VPN --> Tor notation please?

I have repeatedly seen people describe combining Tor and a VPN using the following notation: Tor --> VPN  or VPN --> Tor or even Tor --> VPN --> Proxy but then not provide any real-world example of how this is set up.
For example, does Tor --> VPN mean that I have a VPN client running on my Mac through which all of my traffic is tunnelled, then point Firefox to a locally running instance of Tor thereby all of my Tor  traffic is running inside of the VPN tunnel?
Or is it something else entirely? Can somebody please give me a concrete example of each setup?
Edit: I really should've added an example of what I was talking about, I was primarily referring to the examples given in the Tor wiki on the subject.

A:

Quite simple. You are taking the first protocol and routing it through the second protocol. The page you mention discusses the benefits of each one and gives the details.
As an example if you want to run a Tor relay, but don't want your ISP to know you are doing so, you would wrap the Tor traffic in a VPN session, or Tor-over-VPN, written Tor --> VPN. The VPN provider knows what IP you connected from, but not where you are connecting to. Your ISP won't know you are running a relay.
Different methods are achieved in different ways, but one way to do Tor --> VPN is by running the VPN on your router and the Tor client/relay on your computer.
The drawbacks of this complexity is you add latency to increase security.

