ACID (Atomicity, Consistency, Isolation, Durability) in IT is a properties of a business (or database) transactions, that guarantees the reliability and data integrity of the transaction.

• Atomicity - transaction as one unit. If one operation of transaction fails, the transaction is failed
• Isolation - concurrent transactions are shielded form the "effects" of other transactions
• Consistency - from one consistent database state to another to another consistent database state
• Durability - guarantees that once a transaction is committed, changes will survive any system failures