Shader Stage refers to the part of the shader pipeline a Node or Port is part of. For example, Vertex or Fragment.
In Shader Graph, Shader Stage is defined per Port but often all Ports on a Node are locked to the same Shader Stage. Ports on some Nodes are unavailable in certain Shader Stages due to limitations in the underlying shader language. See the Node Library documentation for Nodes that have Shader Stage restrictions.
Shader Stage List
|Vertex||Operations calculated per vertex|
|Fragment||Operations calculated per fragment|