A lien is a legally approved claim against a property that allows the lien holder to be paid when the property is sold or refinanced, unless the debt is settled beforehand.
In some cases a lien can transfer property to another if the debt obligation isn’t fulfilled. A plumber or roofing contractor can put a lien on your home if you don’t pay for their services. In essence, a mortgage company has a lien against your property for the outstanding loan amount until you have paid off the loan.
It is difficult for a credit card company to obtain a lien on your property for past due balances, but not impossible.
No one can obtain a lien without first obtaining a judgment against you for the amount you owe.