Here's a breakdown:

* Isostasy describes the balance of forces between the Earth's crust and the mantle. It's like a giant balancing act:

* Continents, being less dense than the underlying mantle, "float" higher. Think of a block of wood in water, it sits higher than the water level.

* The depth to which a continent sinks is determined by its density and thickness. Denser continents sink deeper than less dense ones.

* Mountains, being even less dense, rise higher.

Key points:

* Isostasy is a dynamic process, meaning it's constantly adjusting.

* The weight of mountains and glaciers can depress the Earth's crust, while the removal of glaciers can cause the land to rebound.

* Isostasy is crucial for understanding the formation of mountains, the movement of tectonic plates, and the overall structure of the Earth.