A part allows you to define a discrete area inside a class or a component. Parts can be connected to other parts or to ports, either directly or via a port on the outside of the part.
You connect a part to another part by way of an assembly connector. You connect a part to a port on the outside of a class or component by way of a delegation connector.
A part can be created in the following diagrams:
You can only create a part within a class or a component. If you attempt to drag a part outside of its enclosing classifier, the classifier will grow to continue to enclose it.