A bone is a rigid organ that is part of the skeleton of most vertebrates. Bones protect other organs in the body, produce red and white blood cells, store minerals, provide structure and support for the body, and allow for mobility. Bones come in a variety of shapes and sizes and have a complex internal and external structure. Lightweight yet strong and sturdy, they serve multiple functions. Bone tissue (bone tissue), also known as bone in multiple senses of the word, is hard tissue, a type of specialized connective tissue. It has a honeycomb matrix inside which provides stiffness to the bone. Bone tissue is made up of different types of bone cells. Osteoblasts and osteocytes are involved in bone formation and mineralization; Osteoclasts participate in the resorption of bone tissue. The modified (flattened) osteoblasts become the coat cells that form a protective layer on the bone surface. The mineralized matrix of bone tissue has an organic component consisting mainly of collagen called ossein and an inorganic component consisting of bone minerals made up of various salts. Bone tissue is mineralized tissue of two types, . Other types of tissue found in bones include bone marrow, endosteum, periosteum, nerves, blood vessels, and cartilage. There are about 300 bones in the human body at birth; Many of them fuse during development, leaving a total of 206 separate bones in the adult, not counting the many small sesamoids. The largest bone in the body is the femur, or thighbone, and the smallest is the stirrup in the middle ear. The Greek word for bone is ὀστέον (“osteon”), hence the many terms that use it as a prefix, such as B. Osteopathy. In anatomical terminology, including the international standard Terminologia Anatomica, the word for bone is os (e.g. os breve, os longum, os sesamoideum).