As you work in Maya, most of your actions create nodes in the construction history of the objects you work on. At each point in your work, the current scene is the result of all the nodes you’ve created so far.
For example, you can revolve a curve around a centerpoint to create a new surface with a cross-section in the shape of the curve. When you apply this action to the curve, a new revolve node is created. The new node has the shape of the curve as an input. It has attributes that control how it creates the surface from the curve. And it has the resulting surface as its output.