Volcanos - What they are?

A volcano is an opening in a planet's surface or crust where molten rock, ash, and gases escape from below the surface. Volcanic activity tends to form mountains or features like mountains after multiple eruptions.

Volcanoes are found where tectonic plates are being pulled apart or are coming together. an example of this is the Mid-Atlantic Ridge where the tectonic plates are pulling apart. An example of a volcano caused by colliding plates is the Pacific Ring of Fire where volcanoes are formed from the colliding plates. Volcanoes are not usually created where two plates slide past one another. Volcanoes are also formed where there is stretching and thinning of the Earth's crust, (i.e the African Rift Valley).

Volcanoes can be created by "mantle plumes". These known as "hotspots" , for example at Hawaii, these are known to occur away from plate boundaries. Hotspot volcanoes are also found outside of earth such as in the solar system, especially on rocky planets and moons.