Publisher Summary Bone remodeling is a fundamental process by which the mammalian skeleton tissue is continuously renewed to maintain the structural, biochemical and biomechanical integrity of bone and to support its role in mineral homeostasis. The process of bone remodeling is achieved by the cooperative and sequential work of groups of functionally and morphologically distinct cells, termed basic multicellular units (BMUs) or bone remodeling units (BRUs). Changes in the population and/or activities in any component of the BMUs disrupt the harmony of the cellular efforts and leads to changes in bone mass and strength. The cellular activities of bone remodeling units vary within and among the different bones of the skeleton and this variation changes with age, underlying the mechanism of age-related bone loss. This chapter reviews current concepts of bone remodeling with respect to its cellular mechanism, physiological functions, and anatomic variation in cellular behavior.