Reddit, Could you forgive my ignorance and explain to me how the toll roads work? I am a outsider with a rented car

So reddit, Hello I have been in the States before, but never driving and I hadn't even seen a toll road since today, how does it work? Im thinking about taking a road which has a toll, so is it mandatory to pay off or Can I keep driving? because yesterday some people kept driving and I did it as well but it was another road, I don't know how this other road that I am going to take works. So reddit, could you please provide me information about this situation and how what I need to do? Thanks!