A lien is a claim, interest, or right to property or a portion of it, of another person, arising by law or agreement for payment of a debt or liability. A mechanics' lien is a lien in real estate held by a person for labor, service, or materials furnished in connection with the construction or improvement of real estate. This type of lien is codified by the statute of the state which governs the creation, extent, filing, and foreclosure of the lien. The time limitations for filing of the lien and foreclosure of it are set by statute.

For most states, the lien must be verified or sworn under oath and must include the names and addresses of the lien claimant, the owner of the real estate and/or his/her agent, the street address and legal description of the real estate subject to the lien, the amount due or claimed, including an itemized list of labor or materials furnished, the nature of the work performed and when the work began and ended. The time of filing of the lien determines its priority with respect to other liens on the real estate. Please see specific state for details and/or differences.

Black's Law Dictionary Fifth Edition.