The pharmaceutical industry is attempting to discover thin films as a new drug delivery system. Thin films have been described as an alternative approach to conventional dosage forms. They are a versatile platform that provides fast, local, or systemic effects. Additionally, these systems can be easily applied by themselves, especially for dysphagia patients, geriatric, pediatric, or bedridden patients, as well as patients who cannot easily access water. These drug delivery systems can be administered in various ways such as orally, buccally, sublingually, ocularly, and transdermally. This review examines oral thin films in all aspects from today’s point of view and gives an idea about the growing market share in the world due to the increase in research fields and technological developments. At the same time, it provides an overview of the critical parameters associated with formulation design that affect of thin films, including the design of thin films, anatomical and physiological limitations, the selection of appropriate manufacturing processes, characterization techniques, and the physicochemical properties of polymers and drugs. It also provides insight into the latest thin-film products developed by various pharmaceutical companies.