The study of thin film surface morphology and microstructure is still one of the most intriguing and challenging research areas in thin film science and technology. The geometrical structure and crystal orientation of the thin film growth front formed by the physical vapor deposition technique are controlled by many factors including: surface diffusion, sticking coefficient, and shadowing. Instabilities of growth can occur if the shadowing is more dominant compared to other surface effects and can lead to many diverse physically self-assembled 3D quasi-periodic nanostructures. In this talk I will discuss the fundamental nucleation and growth mechanisms of isolated islands resultant from the shadowing effect in an oblique angle deposition configuration (which becomes a glancing angle deposition when the angle between the incident flux and the surface normal is close to 90o). We explain the formation of the quasi-periodic nature of the islands, which transform into a columnar structure, by a â?~â?~shadowing lengthâ?Tâ?T concept that is similar to the surface diffusion length in conventional thin film growth. We show that the change in the spatial frequency of the periodicity is a result of the elimination of shorter columns due to the shadowing effect during growth. Another interesting aspect is the dramatic change of crystal orientation of the islands during growth. Typically, the initial islands with random crystal orientations are transformed into a fiber texture structure with a tilt angle (with respect to the surface normal) which is correlated to the angle of the incident deposition flux. Vertices of columns having the highest growth velocity normal to the substrate receive the maximum flux and would dominate the film growth. Most intriguingly, the columns often develop a well defined azimuthal orientation even when the substrate is amorphous. The shadowing effect combined with the geometrical effect is proposed to explain these phenomena.