An atomic transaction is an indivisible and irreducible series of database operations such that either all occur, or nothing occurs.

Consistency ensures that a transaction can only bring the database from one valid state to another, maintaining database invariants: any data written to the database must be valid according to all defined rules, including constraints, cascades, triggers, and any combination thereof.

Isolation ensures that concurrent execution of transactions leaves the database in the same state that would have been obtained if the transactions were executed sequentially.

In database systems, durability is the ACID property which guarantees that transactions that have committed will survive permanently.

A transaction reads data written by a concurrent uncommitted transaction.

A data integrity problem in which one writer of data overwrites the changes of a different writer modifying the same data.

A transaction re-reads data it has previously read and finds that data has been modified by another transaction (that committed since the initial read).

A transaction re-executes a query returning a set of rows that satisfy a search condition and finds that the set of rows satisfying the condition has changed due to another recently-committed transaction.

The result of successfully committing a group of transactions is inconsistent with all possible orderings of running those transactions one at a time.

Multiversion concurrency control (MCC or MVCC), is a concurrency control method commonly used by database management systems to provide concurrent access to the database.

Record locking is the technique of preventing simultaneous access to data in a database, to prevent inconsistent results.

A deadlock is a state in which each member of a group is waiting for another member, including itself, to take action, such as sending a message or more commonly releasing a lock.