Can you explain the concept of isolation in the properties of ACID transactions?

Isolation is one of the properties of transactions in the ACID model, which guarantees that concurrently executing transactions do not affect each other and that their execution results are equivalent to sequential execution.

This means that changes made by one transaction are not visible to other transactions until the first one is committed. Thanks to isolation, issues such as:

• Dirty read — reading uncommitted changes of another transaction.
• Non-repeatable read — when data changes between two reads within the same transaction.
• Phantom read — appearance of new rows matching the query condition between two reads.

Isolation levels (e.g., Read Uncommitted, Read Committed, Repeatable Read, Serializable) determine the degree of protection against these problems and affect performance.

Example: if two transactions try to modify the same account simultaneously, isolation guarantees that changes are applied sequentially to avoid inconsistent data.