Transaction is the context of database operations that should act to be single unit of work.

▪ Should fully complete the operation or if something fail, it should rollback the whole operation and go back to consistent state.

▪ ACID - Atomicity, Consistency, Isolation, and Durability

▪ If one change fails on database, the whole transaction is going to fail, and the database should remain in the previous state.

▪ Relational Databases are providing ACID principles to ensure Data Consistency.

▪ If you need strong consistency, its good to choose Relational Databases

https://www.ibm.com/docs/en/cics-ts/5.4?topic=processing-acid-properties-transactions