In reply to BobF.

That's why Citi Virtual Account Numbers is such a great feature. The number, expiration, and CVV code are all different for each instance. I have dozens of different Citi numbers used with online vendors. If one gets compromised via a hack, Citi will just turn it off without needing to issue me a new physical card. And I have control to change the expiration date and max charge amount any time I want as well.