Pericarditis refers to swelling and irritation of the pericardium, which is the thin, saclike tissues surrounding the heart, usually leading to sharp chest pain. This condition can arise due to viral infections, but the cause is often unknown. In this book, various causes and types of pericarditis are elucidated, and treatment options are outlined across six chapters. Chapter One deals with Dressler syndrome, which is secondary pericarditis that occurs after myocardial injury and is widely purported to be of autoimmune etiology. Chapter Two discusses the treatment of pericarditis and the management of potential complications. Chapter Three addresses the clinical and diagnostic features of purulent pericarditis, which is the presence of suppuration in the pericardium, as well as therapeutic options. Chapter Four emphasizes the emerging adverse events of vaccine-induced pericarditis, summarizing its epidemiology, pathogenesis, clinical presentation, diagnosis, management, and limitation. Chapter Five concerns constrictive pericarditis, which arises due to the scarring and loss of elasticity in post-acute pericarditis. Finally, Chapter Six addresses the clinical and diagnostic features of COVID-19-induced pericarditis, as well as the therapeutic options.