The creation of a 3D scene needs at least three key components: Models, materials and lights. In this part, the first of these is covered, that being modeling. Modeling is simply the art and science of creating a surface that either mimics the shape of a real-world object or expresses your imagination of abstract objects.
Depending on the type of object you are trying to model, there are different types of modeling modes. Since modes are not specific to modeling they are covered in different parts of the manual.