Primary • To conduct a long term observational safety (adverse events (AEs) and serious AEs (SAEs) and AE of special interest (AESI)) and efficacy (clinical response according to the PedACR30/50/70/90/100 criteria, JADAS 10 criteria and proposed criteria for inactive disease and remission) registry of in label treatment with an approved biologic (also including their approved biosimilars) or targeted synthetic DMARD (tsDMARD) in systemic onset juvenile idiopathic arthritis (so-JIA), extended oligoarthritis (extOA), psoriatic arthritis (PsA), enthesitis related arthritis (ERA) and polyarticular juvenile idiopathic arthritis (pJIA). Secondary • To assess the long-term efficacy on remission of the respective approved biologic or targeted synthetic DMARD and the long term efficacy on joint erosion, joint damage and treatment adherence in subjects with so-JIA, extOA, PsA, ERA and pJIA. • To identify potential predictors of clinical response and remission. • To assess treatment duration, dosing and reasons for dose modifications. • To assess changes in co-medications, for examples reduction of corticosteroids. • To assess patient growth, development disturbances and bone density (if routinely available). • To assess numbers and incidence rates of adverse events (AEs), AEs of special interest (AESIs) and serious AEs (SAEs). • To assess the occurrence of fractures (fracture rate and location of fractures). • To assess treatment interruptions and treatment withdrawal due to AEs. • To compare incidence rates of adverse events (AEs) and serious AEs (SAEs) observed in JIA patients treated with TNF-inhibiting biologics, Non-TNF-inhibiting biologics or targeted synthetic DMARD and JIA patients treated without biologics but with methotrexate (MTX). These MTX treated patients are already followed in a control registry. This will include but will not be limited to the evaluation of the effect on: bone marrow, liver, lung, kidney, neurological, skin and gastrointestinal, serious opportunistic infections, and malignancies. • To establish different cohorts of children (treated with anti-TNF- biologics ± MTX, Approved biologic ± MTX, or targeted synthetic DMARD ± MTX or MTX alone, not treated with MTX or biologics (after discontinuation of drugs)) each of which will be used as controls for the others.