Busses in Rome

Lets be clear with the terminology. You can buy daily passes for the public transit buses from a Tobacco stand or a booth in the plaza in front of Termini. Might try the TIs also. That gives you the ability to use any bus or tram in the city. Generally the reference to hop on and off bus is the commercial tour buses that follow a fixed route with commentary on the various sites. Again, those tickets are available in the plaza. Second a bus pass does come with the Rome Museum pass. Just be sure to validate the pass when getting on the bus. A little yellow box on a pole near the entrance on the bus.

You can also buy the daily pass from ticket kiosks in the Metro stations or at a ticket window. Cost is 4 euro, and the kiosks give change. Note that the daily pass expires at midnight. You'll only need to validate the pass the first time you get on a bus, but be sure to keep it with you. The daily pass also covers the Metro, and you'll need to use it each time you enter through a turnstyle.

Sally - Frank and Frank give you great advice. There are many spots to buy the daily bus tickets. These three links may help you with the questions you've brought up and supplement their answers! Bus & Metro Tickets in Rome; Kiosks for Bus & Metro Tickets; and Hop on - Hop Off Buses in Rome. You'll find the buses easy to use! Have a great time visiting Rome!

I thought I read on here that the buses were free in Rome?

Buses are free for holders of the Roma Pass. Not actually free: it is just another ticket included in the pass (+ museums + discounts etc.)