A transaction, in computer science, represents a set of operations which lead from a first point of consistency in systems to a second point of consistency if, and only if, all individual operations that are part of the set succeed (in case any of these individual operations fail, the system is returned to the first point of consistency). As an example of a transaction, consider a simple balance transfer from one banking account to another, inside a single bank: in this case, the transaction is based on the account numbers of origin and destination, plus the amount to be transferred. This transaction could be implemented using just two operations: deduct the amount to be transferred from origin account's balance, and then add that same amount to the destination account's balance. However, many error conditions could appear along the process and turn our account data inconsistent: for example, if we detect that the number of the destination account is wrong, after debiting the origin account, the initial debit needs to be reversed (to recover the consistency that existed before we began executing the operations comprising this transaction).
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