Client and server roles in one exchange
A --request for data--> B
A <--response with data-- B

A is the client: it sends this request.
B is the server: it handles the request and sends the response.
If B asks C for data, B is the client in that second exchange.
The same computer can run software in both roles.

A remote original and a saved local copy are on different machines,
even when the copies contain the same data.
The arrows show direction; they do not establish permission or encryption.