A more thorough explanation:

A lien waiver is a legal document that waives or gives up a person's right to place a lien on a property. A lien is a legal claim against a property that can be used to secure payment for work done or materials provided. A lien waiver is usually signed by a subcontractor in the construction industry to allow the owner or general contractor to receive a draw on a construction loan.

For example, if a subcontractor works on a construction project and is owed money, they may have the right to place a lien on the property to ensure payment. However, if they sign a lien waiver, they are giving up that right and cannot place a lien on the property.

Another example of a waiver is a jury waiver. In a criminal trial, a defendant may choose to waive their right to a trial by jury and instead have the trial conducted before a judge.

Overall, a waiver is a voluntary relinquishment or abandonment of a legal right or advantage. It can be express or implied, and may be reinforced by reliance or estoppel.