A Bought ledger is a system in accountancy by which a business records and monitors its creditors. The purchase ledger contains the individual accounts of suppliers from whom the business has made purchases on credit. Information on invoices and credit notes received, and payments made, are recorded in the supplier's account using the debits and credits system, with the balance of each account at a given moment representing the amount currently owed to that supplier.
Historically, the purchase ledger was maintained in book form, hence the term ledger, but in modern practice it is much more likely to be held on computer using accountancy software or a spreadsheet.
The purchase ledger will ordinarily hold a credit balance, unless credit notes or over-payments exceed the credit balance.