Secured credit card
A credit card backed by a cash deposit you make up front, usually equal to your credit limit. It is a common first card for building credit.
You give the card issuer a deposit, for example $500, and get a credit limit up to that amount. You use and pay the card like any other credit card, and many issuers report your payments to the three credit bureaus.
You usually get the deposit back when you pay off the balance and close the account, or when the issuer moves you to a regular card. Secured cards often have higher APRs and fees than unsecured cards, so paying in full matters.
Example
A $500 deposit gives a $500 limit. A $45 phone bill on the card uses $45 ÷ $500 = 9% of it.