Oral mucosa shows specializations, which allow it to fulfill several roles. It protects mechanically against both compressive and shearing forces. It provides a barrier to micro-organisms, toxins and various antigens. It has a role in immunological defense, both humoral and cell-mediated. Minor glands within the oral mucosa provide lubrication and buffering as well as secretion of some antibodies. The mucosa is richly innervated, providing input for touch, proprioception, pain and taste. All these functions of oral mucosa are the main constituents of this chapter.