What is the interior structure of the Earth? We will start our exploration of the Solar System with our home planet Earth. This lecture discusses the interior structure of the Earth, introducing the idea of differentiation, how geologists map the interior of the Earth using seismic waves, and the origin of the Earth's magnetic field. I describe the basic properties of the crust of the Earth, its division into rigid tectonic plates, and describe how plate motions driven by convection in the upper mantle have shaped the visible surface of our planet over its dynamic history. Recorded 2007 Oct 30 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.