Knowledge of the normal state of the oral mucosa is a prerequisite for accurate diagnosis of its diseases. Normally, the mucous membrane of the oral cavity has a smooth shiny surface, and the intensity of the gloss is directly influenced by the degree of its moistening with the oral fluid. The color of the mucous membrane ranges from pale pink to red, depending on the degree of vascularization of the underlying connective tissue. The mobility of the mucous membrane depends on its topography and is determined by the presence of a well-developed submucous layer. The most mobile mucous frill of the lips, cheeks, floor of the mouth, soft palate in contrast to the mucous membrane of the gums and hard palate.