Explain the level of transaction isolation where uncommitted data can be read, and what characterizes it.

The transaction isolation level at which uncommitted data can be read is called Read Uncommitted.

Characteristics of this level:

• A transaction can see changes made by other transactions that have not yet been committed.
• This can lead to the phenomenon of "dirty read," where data may be changed or rolled back later.
• It provides minimal isolation, which increases performance but reduces data integrity.

Example: if transaction A updates a record but has not yet committed, transaction B at the Read Uncommitted level can read these changes. If transaction A then rolls back, the data read by transaction B will be incorrect.