What are the three divisions of plagues of Egypt?

The plagues of Egypt are traditionally divided into three groups of three, followed by the final plague. The first division includes the first three plagues: Water turned to blood, frogs, and lice. The second division features the next three: flies, livestock disease, and boils. The final division consists of the last three plagues: hail, locusts, and darkness, culminating in the death of the firstborn.