Transaction

A transaction is an agreement between two or more parties that creates obligations to perform actions. It may involve transfer of money, goods, or information. In common usage, it refers to a commercial exchange, while more formal definitions appear in accounting, law, and information technology.

In economic and business contexts, a transaction is the act of selling or purchasing goods or services. The value exchanged, formalized by contract or receipt, can be monetary or in-kind. Transaction costs are the costs associated with making an economic exchange, including search, bargaining, and enforcement. Transactions can be consumer purchases, business-to-business trades, or financial transfers.

In accounting, a transaction is an economic event that can be measured and recorded in financial statements. The double-entry system records each transaction in at least two accounts, maintaining the accounting equation: assets = liabilities + equity. Transactions are typically captured via journal entries and reflected in ledgers and reports.

In computing, a database transaction is a unit of work that must be completed in full or not at all. It follows ACID properties: Atomicity, Consistency, Isolation, and Durability. Transactions ensure data integrity in the presence of errors, crashes, or concurrent access. They support operations like insert, update, delete, and are managed by transaction managers or DBMS.

In modern payments and digital currencies, transactions are the records of value transfer. In blockchain and distributed ledger systems, transactions are broadcast, validated by network nodes, and grouped into blocks for append-only ledgers. They can specify inputs and outputs, scripts, and permissions.