Solid Geometry
Solid Geometry is the geometry of threedimensional space, the kind of space we live in.
Three Dimensions
It is called threedimensional, 
Simple Shapes
Let us start with some of the simplest shapes:
Properties
Solids have properties (special things about them), such as:
 volume (think of how much water it could hold)
 surface area (think of the area you would have to paint)
 how many vertices (corner points), faces and edges they have
Polyhedra and NonPolyhedra
There are two main types of solids, "Polyhedra", and "NonPolyhedra":
Polyhedra (they must have flat faces):
Cubes and Cuboids (Volume of a Cuboid) 

Platonic Solids  
Prisms  
Pyramids 
NonPolyhedra (when any surface is not flat):
Sphere  Torus  
Cylinder  Cone 
 Polyhedron Models
 Volume and Area of a Sphere Calculator
 Spheroid
 Cross Sections
 Vertices, Faces, and Edges
 Cone vs Sphere vs Cylinder
 Pyramid vs Cone
 Prism vs Cylinder
 Pyramid vs Cube
 Volume of Horizontal Cylinder
 Euler's Theorem
 Pythagoras in 3D
 Hypercubes