This chapter introduces the essential building blocks of 3D geometry by first extending the 2D tools from Chapters 2 and 3 to 3D. But beyond that, we will also encounter some concepts that are truly 3D, that is, those that do not have 2D counterparts. For example, we examine the cross product, planes, and volume with the scalar triple product. With the geometry presented in this chapter, we will be ready to create and analyze simple 3D objects, which then could be utilized to create complex objects. An application of lighting and shading in computer graphics is used to demonstrate the concepts and describe color interpolation based on barycentric coordinates in a plane. Sketches and figures illustrate the concepts.