Most Americans own between 2 to 4 credit cards per person.
Myself I have 3 credit cards with one from Capital One another from Chase Credit Card and a Walmart Credit Card.
It's best to not have any more than 5 credit cards open because it can harm your credit score and be hard to keep up with the payments.
Only apply for the credit cards that you can reasonably pay off and use responsibly to keep your credit score at a good number.
A low credit score can hurt your chances of getting any futures loans, hurt your chances of getting good insurance rates as well as loan interest rates and can affect your ability to get some jobs.