In computer science, transactions are operations that cannot be divided, and transaction processing is information processing divided into individuals. A transaction must succeed or fail as a complete unit, there cannot be a partially completed transaction.
For example, when you buy a book at an online bookstore, you exchange money for a book (by way of credit). If your credit is good, a series of related actions will ensure you get the book and the bookstore will receive your money. However, if a single operation in that sequence fails at transaction time, the entire transaction fails. You can't get the book, and the bookstore won't receive your money. The technology responsible for the balance and predictability of transactions is called transaction processing.