Vertex Groups
Named sets of vertices with weights
Also known as: Blender vertex group · Blender vertex weights · Blender weight group · Vertex group modifier
Definition
A vertex group is a named set of vertices in Blender, where each vertex has a weight from 0 to 1. Vertex groups are used for many things: bone influence in an Armature, limiting a modifier or shape key to part of a mesh, controlling hair, masking, and driving materials. When you parent a mesh to an armature with Automatic Weights, Blender creates one vertex group per bone and fills it with weights.
In production
Assign vertices in Edit Mode with the Assign button, or paint them in Weight Paint Mode. Name groups after bones exactly, because the Armature modifier matches names. Many modifiers have a Vertex Group field, which is a fast way to apply an effect only where you want it, such as a thicker area with Solidify. Clean up unused groups before export.