ACID (an acronymn for Atomicity Consistency Isolation
Durability) is a concept that Database Professionals generally look for when
evaluating databases and application architectures. For a reliable database all
this four attributes should be achieved.
Atomicity: is an all-or-none proposition.
Consistency: guarantees that a transaction never leaves your database in
a half-finished state.
Isolation: keeps transactions separated from each other until they're
finished.
Durability: guarantees that the database will keep track of pending
changes in such a way that the server can recover from an abnormal termination.
Above
four rules are very important for any developers dealing with databases.