ACID

Atomicity - Transactions

Atomicity guarantees All or Nothing. A set of instructions are executed as an atomic unit. On failure all instructions are reverted to the original state.

Consistency - Constraints, Cascades and Triggers

Consistency ensures all the data is consistent. A set of rules defined by the application are conformed with when any changes are carried out.

Isolation - Locks

Concurrent operation doesn't intefere with each other. If two transactions tries to work on same data then they should operate on it as if they were the one only running.

Durability - Transaction Log files, Replication

Durability means that if all committed transactions should persist even in the case of a system failure.