Individuals can apply for a credit card at 18 years old, but they must demonstrate the ability to pay as stipulated by the Credit CARD Act of 2009. By age 21, the application process is more straightforward, with no need to prove independent income or secure a co-signer, provided other criteria set by the card issuer are met.
For those under 18, becoming an authorized user on a parent's card is an option, though readiness for this responsibility should be assessed. It's crucial to note that credit card approval hinges not just on age but also on credit history, income and the card issuer's specific requirements.