Deep beneath our feet, the Earth is very hot. While the ground usually feels solid and still, some places have openings called volcanoes. A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up deep inside the Earth, an eruption happens. This can be a spectacular and powerful event to witness.

It is important to know the difference between magma and lava. When the melted rock is still underground, scientists call it magma. Once it breaks through the surface and flows out of the volcano, it is called lava. Lava can be as hot as 2,000 degrees Fahrenheit! As lava cools down, it turns back into hard, solid rock. Over millions of years, this cooled rock can build up to form tall mountains or even new islands in the middle of the ocean.

Not all volcanoes erupt in the same way. Some volcanoes are like a shaken-up soda bottle. They explode suddenly, sending clouds of ash and hot rocks high into the sky. Other volcanoes are much calmer. Instead of exploding, the lava slowly leaks out and flows down the sides like thick, glowing syrup. These different styles of eruptions happen because of the different types of gases and minerals found inside the magma.

Scientists who study volcanoes are called volcanologists. They put volcanoes into three different groups to describe how they behave. An "active" volcano is one that has erupted recently and could erupt again at any time. A "dormant" volcano is like a sleeping giant; it hasn't erupted in a long time, but it might wake up in the future. Finally, an "extinct" volcano is one that scientists believe will never erupt again.

Volcanoes are powerful and can be dangerous, but they also help our planet. When volcanoes erupt, they bring minerals from deep inside the Earth to the surface. These minerals make the soil around volcanoes very rich and fertile, which is great for growing plants and farming. Volcanoes are a fascinating reminder that our Earth is constantly changing and moving beneath our feet.