New SBB rail user question - do we need tickets in advance

Tiepoumbiemb23

Hello we are from US and never used Swiss rail. So, sorry for this simple question.

Is it necessary to book Zurich airport to Zurich Hauptbaunhof rail in advance or can we just show up and buy tickets at the station that day?
Same question for Zurich Hauptbaunhof to Luzern: Do we need to buy tickets in advance or can we purchase the same day of travel at the train station?
Do the trains fill up?

Krist

Trains are mass transit. Just like you do not buy tickets for subways or commuter rail in advance in the US you do not need to do so in Switzerland. Tickets are always available.
It is of course always possible that more people board a train then there are seats. Then some may have to stand. But that is rare on Swiss trains.