Can someone ELI5 the Katy toll road

I feel stupid asking but I was passing through Houston omw to the east coast when I seen the signs for katy toll road so I just got off the interstate as I didn't see a clear way to avoid the toll or even know how to pay for it lol.

Now I'm headed back and wondering if I should just go around the interstate again or if there is a lane on I10 west that isn't tolled?

Thanks for baring with my probably ridiculous question to anyone who lives there. I will accept the ridicule as long as someone is kind enough to give a proper answer.