Triangulated Irregular Networks (TINs), comprised of vertices, edges, and triangles, are widely used data structures for modeling surface morphology. This article introduces digital terrain model and analysis based on TINs, including the concept of TINs, their compositional forms, the methodologies employed in their construction, and TIN-based terrain factor extractions and applications. The construction of TINs is influenced by various methodologies, leading to the creation of distinct TIN models. Presently, the TIN based on Delaunay triangulation (D-TIN) stands as the most widely adopted model. Built upon D-TIN, a series of terrain derivative calculation methodologies have been proposed, enabling the extraction of slope, aspect, flow direction, and facilitating terrain classification. These enhancements further contribute to the scientific characterization of the morphological features and processes of the Earth's surface topography. Moreover, vectorial calculation methods have been utilized to compute surface terrain derivatives based on TINs, effectively leveraging the attribute of TIN's data structure. Finally, the main application of TIN-based terrain factors has been summarized to provide a beneficial resource for researchers and practitioners in the field.