ACID

ACID is the acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.

Atomicity – means a transaction must execute completely or not at all. This means atomicity guaranteed that operations with in a transaction undergo an all-or-nothing paradigm – either all the database updates are performed , or nothing happens is a n error occurs at any time

Consistency – is a transactional characteristic that must be enforced by both the transactional system and the application developer. Consistency guarantees that a transaction leaves the system’s state to be consistent after a transaction completes. Consistency refers to the integrity of the underlying data store. Atomicity helps enforce the system always appears to be consistent.

Isolated – makes a transaction to execute without interference from another process or transactions. Isolation protects concurrently executing transactions from seeing each others incomplete results. Isolation allows multiple transactions to read or write to a database without knowing about each other because each transaction is isolated from each others.

Durability – means that all the data changes made during the course of a transaction must be written to some type of physical storage before the transaction is successfully completed.