A pledge is the delivery of goods by one person to another as a security for the payment of a debt. This may be also for the performance of promise. Pledge is also known as Pawn. It is actually the bailment of goods as a security. Section 172 of the Indian Contract Act deals with a Pledge.
In case of a pledge, the goods are kept with the creditor as a security. The creditor can make use of these goods to pressurise the debtor for payment. He could even dispose it of.
The most important advantage is that the goods cannot be pledged again with some other person/creditor. However this is in the case of actual possession. There may be constructive possession also.
The borrower cannot manipulate with the goods.