In the Exodus story, God sends ten plagues against Egypt before Pharaoh releases the Israelites.
The plagues are presented as signs and judgments that expose the powerlessness of Egypt's gods and pressure Pharaoh to let the Israelites leave. The sequence includes water turned to blood, frogs, gnats or lice, flies, livestock disease, boils, hail, locusts, darkness, and the death of the firstborn. Translation and tradition vary slightly in the wording of some early plagues, but the total number is ten.
The final plague is central to the Passover story. Israelites are instructed to mark their doorposts with lamb's blood, and the destroying force passes over those homes. Pharaoh then permits the Israelites to depart, although Exodus later says he changes his mind and pursues them.
The ten plagues should not be confused with the Ten Commandments, which are a separate group of laws associated with Mount Sinai. They also differ from the later wilderness complaints and miracles.