1. Lithosphere: This is the solid, rocky outer layer of Earth, including the crust and upper mantle. It's what we walk on and where mountains, valleys, and oceans are formed.

2. Hydrosphere: This encompasses all the water on Earth, including oceans, lakes, rivers, groundwater, ice, and even the water vapor in the atmosphere. It's essential for life and plays a key role in Earth's climate.

3. Atmosphere: This is the layer of gases that surrounds Earth, protecting us from harmful radiation and regulating temperature. It's composed mainly of nitrogen and oxygen, and it's where weather occurs.