What is the difference between quads and triangles in 3D modeling?

In 3D modeling, quads (four-sided polygons) and triangles (three-sided polygons) differ primarily in structure, edge flow, and practical applications. Quads feature smoother edge flow, making them easier to subdivide, adjust, and deform—ideal for organic modeling (e.g., characters) or animation where mesh flexibility is critical. Triangles, as the simplest polygon, are more rigid and may cause shading artifacts (like hard edges) but excel in real-time rendering (e.g., games) due to their computational efficiency. For models requiring frequent adjustments or animation, starting with quads helps maintain clean topology, while triangles are preferred for performance-focused, real-time projects.