Have you ever borrowed a toy from a friend and you promised to give it back, but you can only do so when you finish building a Lego house? A lien waiver is kind of like that promise, but for grown-ups who work in construction.
When someone is building something, like a house or a building, they hire other people to do some of the work, like plumbing or electrical work. These people are called "contractors" or "subcontractors." But, just like when you borrowed a toy, these contractors and subcontractors need to get paid for their work.
Sometimes, the person who hired the contractors wants to make sure they don't pay them twice by mistake. So, they ask the contractors and subcontractors to sign a lien waiver. This waiver is like a promise that says, "I promise you have already paid me for the work I did, so you don't owe me anything else."
It's important for both the person who hired the contractors and the contractors themselves to keep track of these lien waivers. That way, everyone knows who has been paid and who still needs to be paid.
So, in short, a lien waiver is a promise from a contractor or subcontractor that they have already been paid for their work on a construction project.