Exodus 9:8-10:29

"By now I could have lifted my hand and struck you and your people with a plague to wipe you off the face of the earth. But I have spared you for a purpose—to show you my power and to spread my fame throughout the earth." v9:15-16
As each gloomy plague descended upon the land, the Egyptian people realized how powerless their own gods were to stop it. Hapi, the god of the Nile River, could not prevent the waters from turning to blood. Hathor, the crafty cow-godess, was helpless as Egyptian livestock died in droves. Amon-Re, the sun-god and chief of the Egyptian gods, could not stop an eerie darkness from covering the land for three full days. The Egyptian gods were:
(1) not personal
(2) numerous
(3) not exclusive (any and all could be worshiped)

By contrast, the Go of the Hebrews was:
(1) a living personal Being
(2) the only true God
(3) the only God who should be worshiped

God was proving to both the Hebrews and the Egyptians that he alone is the living and all-powerful God.

Taken from the NLT Life Application Study Bible