Accounting, also known as accountancy, is the measurement, processing, and communication of financial and non-financial information about economic entities such as businesses and corporations. Accounting, which has been called the "language of business", measures the results of an organization's economic activities and conveys this information to a variety of stakeholders, including investors, creditors, management, and regulators. Practitioners of accounting are known as accountants. The terms "accounting" and "financial reporting" are often used as synonyms.

Accounting can be divided into several fields including financial accounting, management accounting, tax accounting and cost accounting. Financial accounting focuses on the reporting of an organization's financial information, including the preparation of financial statements, to the external users of the information, such as investors, regulators and suppliers. Management accounting focuses on the measurement, analysis and reporting of information for internal use by management. The recording of financial transactions, so that summaries of the financials may be presented in financial reports, is known as bookkeeping, of which double-entry bookkeeping is the most common system. Accounting information systems are designed to support accounting functions and related activities.

Accounting has existed in various forms and levels of sophistication throughout human history. The double-entry accounting system in use today was developed in medieval Europe, particularly in Venice, and is usually attributed to the Italian mathematician and Franciscan friar Luca Pacioli. Today, accounting is facilitated by accounting organizations such as standard-setters, accounting firms and professional bodies. Financial statements are usually audited by accounting firms, and are prepared in accordance with generally accepted accounting principles (GAAP). GAAP is set by various standard-setting organizations such as the Financial Accounting Standards Board (FASB) in the United States and the Financial Reporting Council in the United Kingdom. As of 2012, "all major economies" have plans to converge towards or adopt the International Financial Reporting Standards (IFRS).