ACID is a mnemonic for Atomicity, Consistency, Isolation, Durability. It represents one of the most widely supported (and needed!) set of guarantees from storage systems that involve transactions. An ACID-compliant database provides an environment where a high level of consistency can be engineered without complicating the application. This concept is standardized by the ISO (ISO/IEC 10026-1:1992 Section 4). Let's look at each guarantee in detail.