Nodes can be used to change an object's geometry in a more complex way than regular modifiers. To use them add a Geometry Nodes Modifier.
Nodes for working with data stored per object element, e.g. vertex groups.
Nodes for modifying color data passed through color sockets.
Nodes that can operate on different geometry types (volume, mesh).
Nodes used mainly as input to other nodes.
Nodes that only operate on meshes.
Nodes that modify the object elements, e.g. vertices.
Nodes with general purpose for modifying data.
Nodes for modifying vector quantities.