componentTags are membership tags that you can define in the Component Tags table. The componentTag node replaces the groupID node and declutters the Node Editor by eliminating Tweak nodes, groupParts, and objectSet nodes. You can use Component Tags expressions to define deformer memberships dynamically as well as define deformer falloffs.
To use Component Tags, you must turn on the Component Tags option in the Rigging section of the Animation (Settings) Preferences. This way, componentTags are used instead of groupID nodes whenever you use deformers.
Use Assign Component Tags to geometry to create Component Tag memberships using the Component Tags table.