A lien is any official claim or charge on a piece of property, known as collateral, for payment of a debt owed or for some agreed upon service. A lien is usually in the form of a legal document that is signed by the one who is owed money in addition to the one who owes the money and is agreeing to the amount to be repaid. With a lien comes the right to sell the property if the contract is broken, in order to recover the money if necessary.