What ACID Means
A stands for atomicity, which means that given a transaction containing multiple SQL statements, then when the transaction completes, all or non of the statements must be committed to the database.
C stands for consistency. This means that a transaction will take the database from one consistent state to another, in order words, only valid data can be written to the database.
I stands for isolation, which means that an operation cannot access data that has been modified by another operation’s transaction, until that transaction has been committed to the database.
D stands for durability. This means that once a transaction has been committed, then the database won’t loose that transaction’s data.