An authorized user is someone allowed to use another person's credit card account. You get your own card with your name on it, you can make purchases with it, but you are not legally responsible for paying the bill. The primary cardholder owns the debt. For families, that structure makes the authorized user setup one of the simplest ways to help someone build credit.
Why it helps. When an issuer reports an authorized user account to the credit bureaus, the entire history of that account appears on the authorized user's report: its age, its payment history, and its balance relative to its limit. A ten-year-old card that has always been paid on time and kept at a low balance can therefore give a newcomer an instant record that looks years old. That is also why it pairs naturally with a first secured card. The authorized user account supplies history while the newcomer's own card supplies a record in their own name.
Picking the right card matters more than picking any card. The ideal account is old, has a perfect payment record, and carries a low balance relative to its limit. A new card with a high balance helps little and can hurt, because the authorized user inherits the utilization too. Before adding anyone, check the card's balance and history honestly. If the primary cardholder's habits are uneven, the authorized user setup will pass those habits along.
The risk runs both ways, and the bureaus do not treat it identically. One major bureau suppresses negative authorized user tradelines, meaning a late payment by the primary cardholder may not appear on the authorized user's report there, but other bureaus may show it. The safe assumption is that the primary cardholder's behavior can affect you. Never add someone to a card you struggle to manage, and never accept authorized user status on a card whose owner you do not fully trust.
Exiting is easy, which is part of the appeal. The primary cardholder can remove an authorized user at any time, and the authorized user can also ask the issuer to be removed. Once removed, the account generally disappears from the authorized user's report. That is very different from a joint account, where both people are liable for the debt and where negative history stays on both reports even after the account is closed. If you are choosing between the two, the authorized user setup is the lower-commitment option by a wide margin.
Two planning notes people miss. First, an authorized user account counts toward the Chase 5/24 rule if it appears on your credit report, so a family card can quietly use up one of your five slots. If you plan to apply for Chase cards, count those accounts before you apply. Second, authorized user status does not teach the issuer anything about how you personally handle debt, since you are not the one paying. Lenders still want to see an account in your own name eventually, so treat the authorized user setup as a head start, not a finished product.
How to do it well as a family. Agree on the rules before the card arrives: what the authorized user may buy, who pays for those purchases, and what happens if spending goes beyond the agreement. Keep the primary card's balance low and its payments on autopay. Check the authorized user's credit report after a month or two to confirm the account actually appeared, since not every issuer reports every authorized user. And revisit the arrangement once a year. When the newcomer has their own card and a growing record, the training wheels can come off.