The ten plagues of Egypt were blood, frogs, gnats and lice, flies, diseased livestock, boils, hail, locusts, darkness and the death of the firstborn. The plagues occurred when the pharaoh would not let the Israelites go into the wilderness to celebrate their religious rites. Moses attempted to convince the pharaoh by turning his staff into a snake, but when court magicians repeated the transformation, the pharaoh was unconvinced.
As the plagues began in Egypt, the court magicians attempted to calm the pharaoh by showing that they were just magic tricks. Indeed, the magicians were able to replicate the effects of the Nile turning into blood and the plague of frogs, but the scale of the plagues quickly outstripped their talents for prestidigitation. Several times during the plagues the pharaoh relented and agreed to let Moses and his people go, only to change his mind once the plague ended.
Each of the plagues was geared toward a particular Egyptian god or gods, in order to embarrass them and display the power of the Hebrew God. For instance, the livestock plague showed how powerless Hathor was to protect farm animals, and the plague of darkness showed that Ra was not the true ruler of the sky. The death of the firstborn was aimed directly at the pharaoh and his household, and it finally won the Israelites their freedom.