What does the term ACID mean with respect to databases?

ACID covers 4 properties that Database transactions should have. A stands for Atomicity - either all the work done as part of a transaction should finish or none of it should. C stands for consistency i.e. any changes done by a transaction should pass all validation rules . I stands for Isolation which refers to the idea that transactions should be able to execute correctly independently of other concurrent transactions. D is for Durability. Any work done by a transaction that commits should persist despite failures. Each of these terms requires a more detailed explanation but this is a high level overview of the term ACID in databases