This document discusses juvenile arthritis (JIA), the most common cause of chronic arthritis in childhood. It describes different classification systems for JIA, including the current ILAR classification which divides JIA into 7 subtypes based on symptoms. The subtypes include systemic, oligoarticular, and different types of polyarticular JIA. It also discusses investigations, treatment options including medications and physical therapy, as well as complications and prognosis for each JIA subtype.