ACID properites stand for Atomicity, Consistency, Isolation and Durability.
Reliable transaction must satisfy these ACID properties.
Atomicity means either all or nothing to be done.
A transaction is Automic, should satisfiy following conditions,
Whole of the transaction must be rolled back if any part of transaction fails.
Transaction must be committed only if all parts of transaction is successful.
Consitency means that each transaction will ensure that database remains in a valid state.
Once the transaction is complete, it should satisfy all the constraints, triggers, rule etc..
Isolation means that each transaction can be executed in separately.
Each transaction is possible to run in a concurrent system.
Incomplete transaction will not be visible to another transaction.
Durability means that changes done by a transaction are permanent.
Even if database crashes or power goes off, committed transaction and results must remain stored.