When I have reviewed some of the criticisms of connecting shapes in Visio on the web, it has been clear that some users have a misunderstanding about lines and connectors. It is not surprising really because the Microsoft Visio help documentation does not currently make the distinction clear. A connector shape is used to connect two shapes together, whereas a line is normally just a straight line. As usual with Visio though, this is not the whole story because a line can be used to connect two shapes together, and it can be turned into a dynamic connector. I will try to explain myself in this article.
The normal way to connect two shapes together is to use the Connector tool (CTRL+3) on the Home / Tools ribbon, and a line is drawn with the Line (CTRL+6) drop-down menu in the same ribbon group.