Volcanoes are openings in the Earth's surface where molten rock, ash, and gases can escape from below. They are formed by tectonic activity and can vary in size and shape. Some volcanoes erupt explosively, while others have gentle lava flows. Famous examples include Mount St. Helens and Kilauea. The study of volcanoes, known as volcanology, helps scientists understand their behavior and predict eruptions. This knowledge is crucial for the safety of nearby communities. Monitoring tools like seismographs and gas sensors are used to detect changes in volcanic activity, providing early warnings to mitigate risks.