§ 1586 Proposal Revocation Before Acceptance

• •You can withdraw an offer at any time before the other person gets the message.
• •Once the other person knows about the offer, you can no longer cancel it.
• •The offer stays open until the other person accepts or you formally withdraw before they hear it.

You tell a neighbor you might sell your lawn mower for $30, but you haven't told them yet that you're actually selling it.

You can change your mind and cancel the offer before the neighbor knows about it, but after they hear you're selling it they can't later claim you broke a deal.