Osteomyelitis is inflammation of the bone and bone marrow that is generally of a bacterial origin. Hematogenous osteomyelitis mainly occurs in infants and children. In adults, osteomyelitis is usually a subacute or chronic infection that develops secondary to an open fracture and the surrounding soft tissue. Treatment of osteomyelitis has improved considerably over the past 30 years because of advances in diagnostic, surgical, and therapeutic techniques. This article provides the current evidence-based medicine in terms of classification, etiology, pathogenesis, diagnosis, and treatment to discuss updated concepts for treating osteomyelitis.