Atomicity. In a transaction involving two or more discrete pieces of information, either all of the pieces are committed or none are.

Consistency. A transaction either creates a new and valid state of data, or, if any failure occurs, returns all data to its state before the transaction was started.

Isolation. A transaction in process and not yet committed must remain isolated from any other transaction.

Durability. Committed data is saved by the system such that, even in the event of a failure and system restart, the data is available in its correct state.

Is MySQL ACID Compliant?

Yes, MySQL has 2 storage engines that are ACID Compliant, Innodb and Falcon. These two engines support transactions and row level locking. This makes it possible for a MySQL server with multiple connections and questions to remain in a consistent state and that each connection does not interfere with another.

I will write a post listing differences of storage engines and how to select one for you tables.