Angiotensin Receptor Blockers (ARBs) are medications primarily used to treat hypertension, heart failure, and chronic kidney disease. They work by blocking the angiotensin II type 1 receptor (AT1R), thereby preventing the vasoconstrictive and aldosterone-releasing effects of angiotensin II within the renin-angiotensin-aldosterone system (RAAS). The development of ARBs was built upon the discovery of RAAS in the early 20th century, followed by the introduction of ACE inhibitors in the 1970s and 1980s. However, due to side effects associated with ACE inhibitors, such as cough and angioedema, ARBs emerged in the 1990s as a more targeted alternative, with losartan becoming the first FDA-approved ARB in 1995.