Myocardium is a thick contractile middle layer of uniquely constructed and arranged muscle cells that forms the bulk of the heart wall. Myocarditis is clinically and pathologically defined as “inflammation of the myocardium”. Clinical presentations of the disease range from nonspecific systemic symptoms (fever, myalgias, palpitations or exertional dyspnea) to fulminant hemodynamic collapse and sudden death. Myocarditis most commonly results from an external inflammatory trigger, such as a virus, including a host immune response that may range from minimally transient response to fulminant, overwhelming inflammation. The pathogenesis of myocarditis is explained. Clinical manifestations range from asymptomatic electrocardiogram (ECG) abnormalities to cardiogenic shock. Myocarditis can produce variable effects on the cardiac conduction system. Ventricular tachycardia is an uncommon initial manifestation of myocarditis but often develops during long-term follow-up. Diagnostic evaluation is done through biopsy, cardiac biomarkers, immunologic markers, and myocardial imaging. Natural history and prognosis, treatment, future directions, pericarditis, pericardial effusion, and laboratory investigations are presented.