Debit and credit note

A debit note (also known as debit memo) can be issued from a buyer to their seller to indicate or request a return of funds due to incorrect or damaged goods received, purchase cancellation, or other specified circumstances.In other words, a debit note basically acts as a buyer's formal request for a credit note from the seller. The document therefore serves as evidence to support a purchase return in the accounting books of a buyer.A credit note or credit memo is a commercial document issued by a seller to a buyer. Credit notes act as a source document for the sales return journal. In other words the credit note is evidence of the reduction in sales. A credit memo, a contraction of the term "credit memorandum", is evidence of a reduction in the amount that a buyer owes a seller under the terms of an earlier invoice. It can also be a document from a bank to a depositor to indicate the depositor's balance is being in event other than a deposit, such as the collection by the bank of the depositor's note receivable

In simple way

When goods are returned to a supplier, a debit note is prepared to represent the difference in the quantity. It contains the name of the party (supplier) whose account has been debited, along with the amount and details of the bill and the reason for the debit, in reference to which his account has been debited.
On the other hand, when goods are received back from the customer, a credit note is sent to him, indicating that the customer’s account has been credited in the books.