There are more than 1500 active volcanoes on the earth. Some people found out that their are 80 or more volcanoes under the ocean. The earths crust is made out of slabs called plates , which fit together like a jigsaw puzzle. These plates sometimes move. The friction causes earthquakes and volcanoes near the edges of the plates , that is called plate tectonics. Also volcanoes helps by releasing the pressure that builds inside the earth.

What is the difference between Lava and Magma ? :

Magma: Is liquid rock inside a volcano.

Lava: Is liquid rock , that comes out of a volcano . Fresh lava ranges from 1,300 to 2,200 F , ( 700 to 1,200 C ) in tempreture and glows red hot to white hot as it glows.