Pulmonary hypertension is a severe disorder defined by an elevated mean pulmonary arterial pressure (mPAP) as >25 mmHg at rest. A classification of the different types of pulmonary hypertension has been established according to shared pathologic and clinical features as well as similar therapeutic options and recently updated. Five major categories have been defined including 1) pulmonary arterial hypertension (PAH), 2) PH owing to left heart diseases, 3) PH owing to lung diseases and/or hypoxia, 4) chronic thromboembolic PH (CTEPH) and 5) PH with unclear multifactorial mechanisms.