A transaction processing system collects and stores data about transactions and sometimes controls decisions made as part of a transaction. The transaction is the activity that changes stored data, examples of such an activity would be using a credit card, making a reservation or making a cash withdrawal at an ATM.
There are two types of transaction processing:
Batch transaction processing: this is information that is gathered and stored but not processed immediately i.e. the processing of an invoice or cheques in a banking system.
Real time transaction processing: this is a transaction which is processed immediately and the operator has access to on-line database i.e. withdrawal from a bank account, Library loans.