What do you understand by the term "Unpaid Seller"? Explain unpaid seller's right to lien.

The seller of goods is deemed to be unpaid seller: When the whole of the price has not been paid or tendered; or When a conditional payment was made by a bill of exchange or other negotiable instrument, and the instrument has been dishonoured. Right of Lien: An unpaid seller in possession of goods sold, may exercise his lien on the goods, i.e., keep the goods in his possession and refuse to deliver them to the buyer until the fulfilment or tender of the price in cases where: the goods have been sold without stipulation as to credit; or the goods have been sold on credit, but the term of credit has expired; or the buyer becomes insolvent. The lien depends on physical possession. The seller's lien is possessory lien, so that it can be exercised only so long as the seller is in possession of the goods. It can only be exercised for the non-payment of the price and not for any other charges.