The tongue, situated within the oral cavity, presents a formidable barrier to imitation due to its unique and inaccessible nature. Its intricate characteristics, spanning shape, texture, and color, provide a rich vein of study for researchers. Investigations have unveiled a notable array of variations in both the ventral and dorsal aspects of individual tongues, underscoring the potential for leveraging these distinctions in authentication protocols. Furthermore, the process of extracting a tongue print is notably uncomplicated when the tongue is protruded from the mouth, adding to its viability as a biometric marker. This paper embarks on a comprehensive review of prior endeavors in the realm of tongue print authentication methodologies. It scrutinizes various tongue print techniques employed and the establishment of comprehensive tongue image databases. By synthesizing and evaluating the existing body of research, this study endeavors to propel the evolution of tongue-based authentication systems forward. Our aim is to not only consolidate existing knowledge but also to illuminate potential avenues for future research and innovation in this burgeoning field of biometric authentication. Through this endeavor, we seek to contribute to the refinement and widespread adoption of tongue-based authentication technologies.