The word Volcano name comes from Roman God of fire 'Vulcan'.Volcanoes are openings in the Earth's surface.In other words, volcanoes are holes in the earth's surface from where hot gases and molten metals come out.As pressure in the molten rocks below the earth builds up,it needs to erupt from somewhere.This inward pressure causes some fissures (cracks) on the earth's crust, and when enough pressure builds up a big hole is crated and lava comes out with lot of force and velocity. Volcanoes can be active ,dormant or extinct.When volcanoes are active,hot magma,ash and gases come out and sometimes it seems it is a source of burning fire.
Hot liquid under the earth's surface is known as magma but when it comes out ,it is known as lava.are like safety valves on the earth's surface,when the pressure builds up inside the earth's surface ,this gets released through these holes.
Volcano for Children,Volcanoes- How they happen. Easy to understand .For children of class 4th & 5th.Educational Videos for Kids