When you add an authorized user to your card, that person can make charges on the card. They also have access to some of the benefits that come with the card.
The additional user will receive their own card, but the primary cardholder is responsible for any charges made on the card.
Adding an authorized user can make sense when you want a household member to receive benefits such as lounge access and other perks. The additional rewards earned from an authorized user’s purchases can also be a plus.