The average American has 19 of these — and experts say we may each have more than 100 within a decade. What are they?

The average American has 19 of these — and experts say we may each have more than 100 within a decade. What are they?

The average American has 19 of these — and experts say we may each have more than 100 within a decade. What are they?
Ans: Passwords.