Infections are common in hand surgery and proper management is important to achieve optimal outcomes. Although most cases are not urgent, less common, severe infections such as flexor tenosynovitis and necrotizing fasciitis require urgent identification with both medical and surgical management. It is common for diagnoses to be missed or delayed because clinical and laboratory indicators are often variably present. Delayed identification and management can result in poor outcomes with permanent deficits. This article will provide a review of hand infections with a focus on identifying serious hand infections requiring urgent or emergent treatment, and distinguishing these from less urgent scenarios.