The document discusses the oral mucosa, including its development, functions, tissue components, and divisions. The oral mucosa is lined by stratified squamous epithelium that can be keratinized or non-keratinized. It has three tissue components - epithelial tissue, lamina propria, and submucosa. The oral mucosa is divided into keratinized areas like gingiva and hard palate and non-keratinized areas like lips, cheeks, and floor of the mouth. Regional variations in the oral mucosa are described for sites like residual alveolar ridges.