TO EVERYONE
thanks for all of this great information. !!!
It seems that the Oyster card is the same type of payment card that I use in the U.S. in New York City. In NY It's called a "Metro card" and you buy the card for 2.50$, then you load in the amount of money you want to store on the card. You can buy the card with cash or use a credit / or debit card to pay for it. I usually put 20.00$ on the card and check at subway stations (on checking machine) to make sure I'm not running out of fare money. this metro card can also be used on the NY City buses (preferred to using cash), since the drivers won't take cash. So I'm familiar with the concept.
so one more comment about the contactless card. I checked my cards and I do have one, but the fees would be ridiculous if I use it...as someone implied in one of the responses. I'll go with the debit card, use my pin and won't get charged.
But one more question for clarification. I've read that there is a fare capping of 7 pounds, so you don't pay more than that in a day. Wondering if that only applies to the Visitor Oyster card, only, which I can't get, since I leave tomorrow from Florida and there's no time for it to get to my house. I'll buy the oyster card at the stations and designated shops.
thanks