The Earth's crust is the outermost layer of our planet, composed of solid rock. It varies in thickness, being thinner under oceans and thicker under continents. The crust is divided into large sections called tectonic plates, which float on the semi-fluid layer beneath them, known as the mantle. This layer is essential for life, as it contains minerals and resources like soil, water, and fossil fuels. The movement of tectonic plates can lead to geological events such as earthquakes and volcanic eruptions, shaping the Earth's surface over millions of years.