As the previous chapter was concluded with the deformation tensor, this tensor is explained further in this twelfth chapter. As this tensor includes both the strain and rotation components, it is useful to derive geologically important parameters. Because of the rotational components introduced in the tensor, the distinction between coaxial and non-coaxial deformation should be explaind. This is therefore done in the first paragraph. In the second paragraph measures for 3D strain and shape parameters for the strain ellipsoid are outlined. Progressive deformation is stretched over two paragraphs. Different homogeneous deformation components are the introduction to the deformation tensor in the sixth paragraph. In the final paragaphs, the defomation tensor is applied to the length of principle stretches  and infinitesimal deformations.