Acid

ACID is an acronym used in computer science to describe four properties of database transactions: Atomicity, Consistency, Isolation, and Durability. A transaction with ACID properties ensures that operations are completed as a unit, leaving the database in a consistent state. Atomicity means that a transaction's changes are all applied or none are; if any part fails, the system rolls back to the prior state. Consistency requires that a transaction transitions the database from one valid state to another, preserving defined rules. Isolation requires that concurrently executing transactions do not interfere with each other, typically achieved through locking or serialization. Durability guarantees that once a transaction has been committed, its effects survive system failures such as power loss.

In chemistry, acids are substances that donate protons (Bronsted-Lowry) or increase hydronium concentration in water (Arrhenius). Common characteristics include a sour taste, the ability to turn blue litmus red, and the tendency to react with metals. The strength of an acid is measured by its dissociation in solution; strong acids fully dissociate, while weak acids partially dissociate. Common examples include hydrochloric acid, sulfuric acid, and acetic acid. The concept is extended to definitions such as Lewis acids, which accept electron pairs, broadening the scope beyond proton transfer.

ACID-focused discussions often contrast with BASE concepts in computing, where BASE describes more relaxed guarantees for scalability and performance. In chemistry, acid theories continue to evolve, integrating multiple models to explain reactivity, structure, and behavior across different solvents and conditions.