ACID (database) definition

ACID stands for Atomicity, Consistency, Isolation and Durability, which is a standard or set of qualities a database system and transaction (data writing and retrieval) has to ensure data remains correct and consistent.

DB transactions that are ACID compliant should ensure that statements either are fully committed or fails completely, the DB has consistent constraints to limit corruption, the management isolates commits done in parallel (to control concurrency and limit conflict) and data successfully written remains intact even after power loss. Unsuccessful transactions must be automatically reversed or never committed and data retrieved must be all up-to-date, correct and not fragmented.