Pharmaceutical formulations are experiencing a significant transformation as novel drug delivery techniques become increasingly available and effective. While there are many different types of medical dosage forms, each has its own limitations, such as tablet choking and painful parenteral dosages. Buccal drug delivery, which involves administering medication to the oral cavity, offers a convenient and easy-to-administer alternative. The oral route of medication administration has numerous benefits, including avoiding liver metabolism, enhancing drug bioavailability, and improving the onset of action. By directly entering the systemic circulation, active pharmaceutical ingredients can produce their therapeutic effects. As the buccal mucosa has a high degree of permeability and blood supply, it is a highly accessible drug delivery system. There are six theories that explain mucosal adhesion: electronics, wettability, adsorption, degradation, diffusion, and mechanics. Various in vitro and in vivo approaches have been used to study buccal drug delivery systems. This paper discusses the mechanisms of action, mucosal adhesion theories, and standard techniques for producing films. Key areas of study in buccal drug delivery systems include evaluating films for weight variation, thickness, folding endurance, surface pH, percentage of moisture absorption and loss, tensile strength, swelling index, content uniformity, and in vitro permeation studies.