A transaction is defined as the unit of work in a database system. Database systems that deal with a large number of transactions are also termed as transaction processing systems. Transaction is a unit of data processing.
E.g.:- Transactions at a Bank may be:
- Withdrawal or deposit of money.
- Transfer of money from A's account to B's account.
A transaction would involve manipulation of one or more data values in a database. Thus, it may require reading and writing of database value.