ACID

Atomicity

• If operations, when grouped together in "atomic" transactions fail to be comitted due to a fault, then the transaction is aborted.
• Abortability could have been a better term

Consistency

• Defines the the database is in a "good state" which is highly subjective because you can violate data rules
• Not a property of a database.
• The application may rely on database's atomicity & isolation properties to achieve consistency (?)

Isolation

• Concurrently running transactions are isolated from each other.

Durability

• Promise that once a transaction has comitted successfully, any data it has written will not be forgotten, even if there's a hardware failure.
• Single node = write to disk
• Distributed = replicate

Reference: DDIA