What credit card do i need to get without credit history existing?

i never had a credit card before, so what one would be good or do i need to get when i dont have credit history existing? idk if i can get one without an existing credit history. im new to credit cards since im only 19 (plus, never had one like i just mentioned). and secondly, what age can i get a credit card without a parent? i thought it was 18, but then when looking i up i found something that said 21, but it also said it is 18 you can start but something about a co-signer.