White lesions in the oral cavity include a wide range of conditions, from benign, harmless entities to oral potentially malignant disorders (OPMDs) and overt carcinomas. These lesions appear white primarily due to the scattering of light as it passes through an altered mucosal surface. White lesions of the oral mucosa arise from various causes, including developmental conditions, reactive changes caused by trauma or smoking, infections, immune-mediated disorders, and potentially malignant or malignant lesions. Features such as symmetry, location, and the appearance of white lesions help to guide diagnosis. This chapter briefly highlights the key features from a clinician’s perspective.