The outer rind of rock is usually referred to as the Earth's crust. It's the outermost layer of the Earth, made up of solid rock and divided into two main types:

* Continental crust: thicker, less dense, and composed mainly of granite. It forms the continents.

* Oceanic crust: thinner, denser, and composed mainly of basalt. It forms the ocean floor.

The crust is the part of the Earth we interact with most directly, and it's where we find all the resources we use, like minerals, fossil fuels, and water. It's also the place where we experience most geological phenomena, like earthquakes and volcanoes.