(1) An exchange between two programs that carries out an action or produces a result. An example is the entry of a customer's deposit and the update of the customer's balance. See also conversation, session.
(2) A unit of processing consisting of one or more application programs, affecting one or more objects, that is initiated by a single request.
(3) A specific set of input data that triggers a specific process or job. A transaction also can refer to a message destined for an application program.
(4) An atomic series of SQL statements that make up a logical unit of work. All of the data modifications made during a transaction are either committed together as a unit or rolled back as a unit. See also multisite update, unit of recovery, remote unit of work, transaction.