Name the levels of transaction isolation.

Transaction isolation levels determine how much a transaction is isolated from modifications made by other transactions. The main isolation levels, according to the SQL standard, are:

1. Read Uncommitted — the lowest level of isolation. A transaction can see uncommitted changes made by other transactions (dirty reads).
2. Read Committed — a transaction only sees data that has been committed by other transactions. It prevents dirty reads but allows non-repeatable reads.
3. Repeatable Read — guarantees that data read during a transaction will not change until the transaction completes. It prevents dirty reads and non-repeatable reads but allows phantom reads.
4. Serializable — the strictest level, providing full transaction isolation as if transactions were executed sequentially. It prevents all anomalies, including phantom reads.

Each level balances between performance and data integrity.