In osteology, the osteon or haversian system (/həˈvɜːr.ʒən/; named for Clopton Havers) is the fundamental functional unit of much compact bone.

The Haversian system forms during the process of endochondral ossification, which starts with a cartilage template that is gradually replaced by bone tissue.

Osteoblasts, the bone-forming cells, secrete the organic components of bone matrix [osteoid] and then initiates its mineralization.

The collagen fiber density is lowest at the seams between lamellae, accounting for the distinctive microscopic appearance of a transverse section of osteons.

[4] In bioarchaeological research and in forensic investigations, osteons in a bone fragment can be used to determine the sex of an individual[5] and age, as well as aspects of taxonomy, diet, health and motor history.