Hypertension, also known as high blood pressure, is a common disease where blood pressure in the arteries is elevated. It has no symptoms but can damage organs if left untreated. There are two types - primary hypertension which has no identifiable cause and accounts for 90-95% of cases, and secondary hypertension which is caused by other conditions affecting the kidneys, heart or endocrine system. Risk factors include obesity, high salt diet, excess alcohol, stress and caffeine. Treatment involves lifestyle changes as well as medications like diuretics, beta blockers, ACE inhibitors and calcium channel blockers to control blood pressure. Regular monitoring of blood pressure and prevention methods can help reduce the risk of hypertension.