Magma is constantly flowing beneath us in Earths mantle, but when it spews out of a volcano, its name switches from magma to lava.
We usually think of volcanic eruptions as something that happens instantaneously and is over in a little bit, like a storm or an earthquake, but in reality, volcanic eruptions can last for decades! For example, Mt. Etna (located in Sicily), has been erupting since 2001.
The word volcano originally comes from the name of the Roman god of fire, Vulcan.
Some famous volcanic eruptions of modern times include Mount Krakatoa in 1883, Novarupta in 1912, Mount St Helens in 1980 and Mt Pinatubo in 1991.
The biggest known volcano isn't even on Earth! Located on Mars, Olympus Mons 600km (373 miles) wide and 21km (13 miles) high.
Even though Earth has a lot of volcanoes, lo, one of Jupiter's moons, has even more. In fact, it has more volcanic activity than any other object in space (that we know of).
Some volcanoes have their lava slowly flow down the side of the volcano, while others spew the lava out, letting it go high in the sky like a firework. The lava can go over 30km (17 miles) above the surface of the Earth!
Large volcanic eruptions can reflect radiation from the Sun and drop average temperatures on Earth by around half a degree. There have been several examples of this over the last century.
Lava comes from the magma in Earth's mantle. Magma is made of rocks that have melted. Things melt (turn from a solid to a liquid) when they get hot. The inside of a volcano is really hot, so when the lava makes it to the surface of the Earth, it cools down like crazy. This causes it to turn back to rock, creating what is known as volcanic rock. One type of volcanic rock, called pumice. This rock can float on water, and is people use it to remove their dry skin.
75% of the worlds volcanoes are located in the Pacific Ring of Fire. This is an area on the pacific ocean where two tectonic plates meet.