Viral, bacterial, and fungal infections are frequently encountered in clinical practice, resulting in numerous cutaneous manifestations. Although diagnosis of these infections has changed over time because of technological advancements, such as polymerase chain reaction, bedside diagnostic techniques still play an important role in diagnosis and management, enabling rapid and low-cost diagnosis and implementation of appropriate therapies. This 2-part article will review both common and infrequent uses of bedside diagnostic techniques that dermatologists can incorporate into daily practice. This article examines the utility of bedside tests for the diagnosis of viral, bacterial, and fungal infections. The second article in this series reviews the use of bedside diagnostics for parasitic and noninfectious disorders.