If your spouse, family member of close friend is not able to apply for a Credit Card by themselves because of some reason than you can help to add he/she to your credit card. The credit card issuer allows you to have an additional person as an authorized user or join account holder. The authorized user is able to spend on your card legally without the responsibility when it comes to paying back the loan. The join account holder much repaying the debt as the primary owner.
By adding someone to your credit card, you grant access to other person into your finance so it has pros/cons for your to consider before making decision. The advantage is you can help someone to build credit score without owning an actual credit card just by joining with you. The bank often prefer the join account holder option because when it come to debt they can collect it from both owners instead of just only you.