Bone tissue refers to the hard, rigid connective tissue that forms part of the endoskeleton of vertebrates. It is composed mainly of collagen fibers and calcium phosphate minerals, which provide strength and rigidity to the bones. Bone tissue also contains bone cells (osteocytes) embedded within a matrix, which help maintain the structure and regulate the remodeling process. The primary function of bone tissue is to support the body's weight, protect vital organs, provide attachment points for muscles, and facilitate movement by serving as levers that muscles can act upon.