I'm so confused. I'm looking for the cheapest way of travel in London from zones 3 to 1 for university. I don't understand what the 18+ student oyster card does, it says something about travel cards. I also don't understand what the 16-25 railcard does, which I was advised to get and combine with the oyster card. What are the benefits of them individually and combined? Do I need the railcard?
Also, can I put the combined cards onto Apple/Google Pay?