A volcanoe is an opening to the earth crust where how liquid called magma erupts to the surface. Magma is very hot and can reach up to 1000 degrees.
Cinder cones - These are volcanoes formed from particles and blobs of lava spew out from a single vent at the top. They generally don't get taller than around 1,000 feet. Composite volcanoes - These volcanoes are also shaped like a cone, but are formed from layers of lava over many years. They can grow into huge mountains over 8,000 feet tall from their base. Shield volcanoes - They form from wide thin layers of lava that eventually are shaped like a shield. Lava domes - these are formed by thick lava that hardens right around the vent. They can sometimes form inside of other types of volcanoes.
When rock beneath the Earth's surface gets really hot, it becomes molten or liquid. When the liquad is on the surface it is called magma. Once the magma erupts to the surface through a volcano, it's called lava. The hotter and thinner the lava is, the farther it will flow. Eventually lava on the surface will stop flowing and cool and harden into rocks. Rocks formed from lava cooling are called igneous rocks.
A volcano can be active, dormant, or extinct. An active volcano is one that has recently erupted or is currently erupting. A dormant volcano is one that hasn't erupted for a long time, but can still erupt. An extinct volcano is one that scientists think will never erupt again but sometimes will erupt.