Vertex Colors

Vertex colors are, just as the name implies, colors stored on the vertices of a mesh.

Note

They can be edited in blender via the vertex paint mode.

Albedo modulation

The most common use case of vertex colors is to apply them to a materials albedo color and transparency via multiplication

A material without (left) and with (right) vertex colors applied to the base color via multiplication in blender

Masking and blending

The second most common use case for vertex colors is to mask or blend multiple layers of textures:

Vertex colors (left) used to blend two different textures together (right) in blender

Other

There are also many other applications for vertex colors, but how and which channel gets used depends entirely on each shader.