Bone is a dynamic connective tissue responsible for important metabolic and mechanical functions. Bones can be classified by their shape and their macroscopic/microscopic structure. The basic unit of bone is the mineralized collagen fibril, and at every level of its organization from the sub-nanoscopic to the macroscopic level it is highly ordered and hierarchical. This structure is directly related to the mechanical properties of cancellous and cortical bone. Bone also contains a population of cells, including osteoblast, osteoclast and osteocytes. The complex interplay between these cell types is responsible for bones metabolic functions and its capability to repair and adapt to stress.