Per-vertex lighting
From Tech Artists Wiki
Per-Vertex Lighting, also known as Gouraud Shading, calculates lighting at each vertex, which is then linearly interpolated between vertices. The result is a polygonal appearance.
Per-Vertex Lighting was a popular method of real time lighting until shaders and Per-Pixel Lighting because available in DirectX 8 and 9. It is mostly used now on mobile and portable devices that lack powerful GPUs.
