A primary credit card is a type of credit card that serves as the main account for an individual. It typically has a higher credit limit and more features than secondary or additional credit cards, which are used for specific purposes such as travel or cashback rewards. The primary credit card is often considered the most important credit card in someone's wallet because it represents their overall creditworthiness and can be used to make purchases, borrow money through cash advances, or build credit history if managed responsibly.