Vertex color properties, also known as color at vertices properties or CAVs, are colors stored in the polynodes (polygon nodes, or sample point) of an object. They can be used for a variety of purposes, such as storing surface color, illumination, or custom data. If necessary, you can store several vertex color properties on the same object.
Every polygon has a polynode for each of its corners, so at a given vertex there are as many polynodes as there are polygons that share that vertex. The color information is interpolated between polynodes — for example, if you paint each corner of a square polygon a different color, then the center of the polygon would display a blend of each of the four colors.
Vertex colors are often used in games because they are an efficient way of storing color information that can be used in a variety of ways, e.g., for pre-baked lighting, texture blending, and so on.
Vertex color properties support 8-bit RGBA values, as well as HDR RGBA values.