A purchase ledger is a system in accountancy

Accountancy

Accountancy is the process of communicating financial information about a business entity to users such as shareholders and managers. The communication is generally in the form of financial statements that show in money terms the economic resources under the control of management; the art lies in...

 by which a business records and monitors its creditor

Creditor

A creditor is a party that has a claim to the services of a second party. It is a person or institution to whom money is owed. The first party, in general, has provided some property or service to the second party under the assumption that the second party will return an equivalent property or...

s. The purchase ledger contains the individual accounts of suppliers from whom the business has made purchases on credit

Credit (finance)

Credit is the trust which allows one party to provide resources to another party where that second party does not reimburse the first party immediately , but instead arranges either to repay or return those resources at a later date. The resources provided may be financial Credit is the trust...

. Information on invoice

Invoice

An invoice or bill is a commercial document issued by a seller to the buyer, indicating the products, quantities, and agreed prices for products or services the seller has provided the buyer. An invoice indicates the buyer must pay the seller, according to the payment terms...

s and credit note

Credit note

A credit note or credit memorandum is a commercial document issued by a seller to a buyer. The seller usually issues a Credit Memo for the same or lower amount than the invoice, and then repays the money to the buyer or sets it off against a balance due from other transactions.It can also be a...

s received, and payments made, are recorded in the supplier's account using the debits and credits

Debits and credits

Debit and credit are the two aspects of every financial transaction. Their use and implication is the fundamental concept in the double-entry bookkeeping system, in which every debit transaction must have a corresponding credit transaction and vice versa.Debits and credits are a system of notation...

 system, with the balance

Balance (accounting)

In banking and accountancy, the outstanding balance is the amount of money owed, , that remains in a deposit account at a given date, after all past remittances, payments and withdrawal have been accounted for. It can be positive or negative ....

 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

Ledger

A ledger is the principal book or computer file for recording and totaling monetary transactions by account, with debits and credits in separate columns and a beginning balance and ending balance for each account. The ledger is a permanent summary of all amounts entered in supporting journals which...

, but in modern practice it is much more likely to be held on computer using accountancy software

Accounting software

Accounting software is application software that records and processes accounting transactions within functional modules such as accounts payable, accounts receivable, payroll, and trial balance. It functions as an accounting information system...

 or a spreadsheet

Spreadsheet

A spreadsheet is a computer application that simulates a paper accounting worksheet. It displays multiple cells usually in a two-dimensional matrix or grid consisting of rows and columns. Each cell contains alphanumeric text, numeric values or formulas...

.