Understanding ACID Transactions

When you transfer money from Account A to Account B, you want to be sure that money doesn't get lost in the middle. ACID properties guarantee this.

A - Atomicity

"All or Nothing." If the system crashes after debiting A but before crediting B, the entire transaction rolls back. Account A's money is restored.

C - Consistency

The database must move from one valid state to another. Constraints (like "Account balance cannot be negative") are enforced.

I - Isolation

Transactions running in parallel shouldn't interfere with each other. If I check my balance while a transfer is pending, I should see consistent data.

D - Durability

Once a transaction is committed, it stays committed. Even if the power goes out 1 second later, the data is saved on disk.

Without ACID, modern commerce would be impossible.