<prompt> Human: I like to keep my finances simple. Ive only recently got my second one for the rewards aspect of it. So for 12 years Ive only had 1 credit card. It doesnt have any rewards so I dont plan on using it. The only reason I can think of is if my new MasterCard isnt accepted, Ill use my old Visa.Whats the best thing for my credit? I was thinking of finding another Visa with better rewards and close my first one? Or just leave it open and dont use it? Will either of these have bad effects on my credit?Any advice would be awesome.  <response>: Keep it open, charge Netflix or some other small amount to it. You want to keep your oldest line of credit open because thats an integral component of credit score. 