The tools in the Curves toolbox are used to create and manipulate B-spline curves.
All tools in a toolbox are not always visible by default. To see all tools, right-click in the toolbox and select Show All from the menu.
Each tool in the Curves toolbox is also a member of a "child" toolbox. When a tool is pointed to and the left mouse button held down, a drop-down menu opens from which a tools in the child toolbox can be selected. The child toolbox can be floated by choosing Open As ToolBox from the drop-down menu.
When a tool is selected in a child toolbox, the tool automatically becomes the "representative" of the child toolbox in the Curves toolbox.
The following table shows the "as delivered" arrangement of the Curves toolbox and identifies the corresponding child toolboxes and for each, the default representative tool: