If the person downloads the Tor Browser and uses it to surf the Internet, is this person also automatically running a Tor exit node or a Tor relay? Or other nodes?
When you download the Tor Browser it acts purely as a client. Your software won't run as an exit node or a relay unless you tell it otherwise. So by downloading the Tor Browser from https://torproject.org/ and running the software you're safe from turning into a server.
Also you don't need to take care of options in your
torrc. Formerly there was the option
ClientOnly, but this is not really used anymore. Instead Tor looks if
ExtORPort are configured. Only in this case Tor turn into a relay.
Neither make you a relay of any sort, they will both act as clients only by default and neither have options to turn them into relays of any sort. You would need to go out of your way to manually change configurations to actually become a relay.
This is by design, it would violate user expectations (principle of least astonishment) and the normal use case for both tails and tor browser (desktop/laptop with a commercial home internet connection) do not make good relays.
Neither of them! =) The default is to use a
ClientOnly 1 i.e. be just a client to Tor network. But it's recommended to become Tor-relay node - it will boost your browsing speed like hell! Make an open external port, better try starting with 443, specify it in
ORPort 443 - and change
ClientOnly 0 in your