In accounting, a ledger is a book or record that contains all the financial transactions of a company. It is a primary source of information for accountants and financial analysts, providing an organized and comprehensive record of a company's financial activities.

Ledgers are typically organized by account type, such as accounts payable, accounts receivable, cash, and inventory. Each account has a separate section in the ledger where individual transactions are recorded. These transactions are then used to create financial statements and reports, such as balance sheets and income statements.

There are two types of ledgers: general ledgers and subsidiary ledgers. A general ledger is the main record of a company's financial transactions, while subsidiary ledgers provide additional detail on specific accounts, such as accounts receivable or accounts payable.

Ledgers can be kept manually in a physical book or electronically using accounting software. Most modern accounting systems use electronic ledgers to maintain accurate and up-to-date financial records.

Keeping an accurate ledger is essential for businesses of all sizes. It allows them to track their financial transactions, monitor cash flow, and prepare financial reports for stakeholders, such as investors and regulatory authorities.

In addition to traditional accounting ledgers, businesses may also use specialized ledgers for specific purposes, such as a sales ledger to track customer orders and payments or a purchase ledger to record supplier transactions.

Overall, a ledger is a fundamental tool for effective financial management, helping businesses to maintain accurate financial records, make informed decisions, and comply with financial reporting requirements.