Pulmonary arterial hypertension (PAH) is a chronic, progressive disease leading to right heart failure and death if untreated. It is classified into five groups based on underlying causes. Group 1 includes idiopathic or familial PAH with or without germline mutations in genes like BMPR2, ACVRL1, ENG, or Smad8. Patients with PAH should be screened for these mutations. Group 2 includes pulmonary hypertension due to left heart diseases, divided into systolic, diastolic, and valvular dysfunction. Group 3 includes pulmonary hypertension due to respiratory diseases, such as pulmonary fibrosis, COPD, or interstitial lung disease. Group 4 includes chronic thromboembolic pulmonary hypertension without distinction between proximal or distal forms. Group 5 includes PH with unclear or multifactorial etiologies. Invasive hemodynamic assessment with right heart catheterization is required to confirm PH, defined by a resting mean pulmonary artery pressure (mPAP) of ≥25 mmHg and a normal pulmonary capillary wedge pressure (PCWP) of ≤15 mmHg. Echocardiography is an important tool in PH management. The European Society of Cardiology and the European Respiratory Society guidelines specify its role in screening. PAH therapy includes non-specific drugs like anticoagulants and diuretics, as well as PAH-specific therapy. Diuretics are important in PH due to right heart failure. Current recommendations propose oral anticoagulation targeting an International Normalized Ratio (INR) of 1.5-2.5. Better understanding of PH pathophysiology has led to the development of medical therapies, though no cure exists. Specific therapies include prostanoids, endothelin receptor antagonists, and phosphodiesterase type 5 inhibitors. The review discusses current epidemiological aspects, diagnostic approaches, and classification of PH. It also discusses current PAH therapy and future treatments. PAH is defined by right-heart catheterization showing precapillary pulmonary hypertension with mPAP >25 mmHg and PCWP <15 mmHg. The classification of PH has evolved since the first classification in 1973. In 2008, the fourth World Symposium on PH revised previous classifications. In 2013, the fifth World Symposium on PH proposed minor modifications. Group 1 includes idiopathic and heritable PAH, drug- and toxin-induced PAH, PAH associated with connective tissue diseases, HIV infection, porto-pulmonary hypertension, congenital heart diseases, schistosomiasis, and chronic hemolytic anemia. Group 1' includes pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis. Group 2 includes pulmonary hypertension due to left heart disease. Group 3 includes pulmonary hypertension due to lung diseases and/or hypoxia. GroupPulmonary arterial hypertension (PAH) is a chronic, progressive disease leading to right heart failure and death if untreated. It is classified into five groups based on underlying causes. Group 1 includes idiopathic or familial PAH with or without germline mutations in genes like BMPR2, ACVRL1, ENG, or Smad8. Patients with PAH should be screened for these mutations. Group 2 includes pulmonary hypertension due to left heart diseases, divided into systolic, diastolic, and valvular dysfunction. Group 3 includes pulmonary hypertension due to respiratory diseases, such as pulmonary fibrosis, COPD, or interstitial lung disease. Group 4 includes chronic thromboembolic pulmonary hypertension without distinction between proximal or distal forms. Group 5 includes PH with unclear or multifactorial etiologies. Invasive hemodynamic assessment with right heart catheterization is required to confirm PH, defined by a resting mean pulmonary artery pressure (mPAP) of ≥25 mmHg and a normal pulmonary capillary wedge pressure (PCWP) of ≤15 mmHg. Echocardiography is an important tool in PH management. The European Society of Cardiology and the European Respiratory Society guidelines specify its role in screening. PAH therapy includes non-specific drugs like anticoagulants and diuretics, as well as PAH-specific therapy. Diuretics are important in PH due to right heart failure. Current recommendations propose oral anticoagulation targeting an International Normalized Ratio (INR) of 1.5-2.5. Better understanding of PH pathophysiology has led to the development of medical therapies, though no cure exists. Specific therapies include prostanoids, endothelin receptor antagonists, and phosphodiesterase type 5 inhibitors. The review discusses current epidemiological aspects, diagnostic approaches, and classification of PH. It also discusses current PAH therapy and future treatments. PAH is defined by right-heart catheterization showing precapillary pulmonary hypertension with mPAP >25 mmHg and PCWP <15 mmHg. The classification of PH has evolved since the first classification in 1973. In 2008, the fourth World Symposium on PH revised previous classifications. In 2013, the fifth World Symposium on PH proposed minor modifications. Group 1 includes idiopathic and heritable PAH, drug- and toxin-induced PAH, PAH associated with connective tissue diseases, HIV infection, porto-pulmonary hypertension, congenital heart diseases, schistosomiasis, and chronic hemolytic anemia. Group 1' includes pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis. Group 2 includes pulmonary hypertension due to left heart disease. Group 3 includes pulmonary hypertension due to lung diseases and/or hypoxia. Group