Pledge is a type of bailment where goods are delivered as security for a debt or obligation. In a pledge, the pledger (pawnor) delivers movable goods like jewelry or documents to the pledgee (pawnee) as collateral for a loan. If the debt is not repaid, the pledgee can sell the goods after providing notice to the pledger. Key requirements for a valid pledge are that the pledger must be the lawful owner of the movable goods provided as collateral, and the goods must be transferred from the pledger to the pledgee. Upon fulfillment of the obligation, the pledgee must return the goods to the pledger and the contract is terminated.