there are quite few buttons in the rbtree applet we'll briefly review what they doalthough at this point some of the descriptions may be bit puzzling soon we'll do some experimenting with these buttons clicking on node the red arrow points to the currently selected node it' this node whose color is changed or which is the top node in rotation you select node by single-clicking it with the mouse this moves the red arrow to the node the start button when you first start the workshop appletand also when you press the start buttonyou'll see that tree is created that contains only one node because an understanding of red-black trees focuses on using the red-black rules during the insertion processit' more convenient to begin with the root and build up the tree by inserting additional nodes to simplify future operationsthe initial root node is always given value of (you select your own numbers for subsequent insertions the ins button the ins button causes new node to be createdwith the value that was typed into the number boxand then inserted into the tree (at least this is what happens if no color flips are necessary see the section on the flip button for more on this possibility notice that the ins button does complete insertion operation with one pushmultiple pushes are not required as they were with the tree workshop applet in the last the focus in the rbtree applet is not on the process of finding the place to insert the nodewhich is similar to that in ordinary binary search treesbut on keeping the tree balancedso the applet doesn' show the individual steps in the insertion the del button pushing the del button causes the node with the key value typed into the number box to be deleted as with the ins buttonthis takes place immediately after the first pushmultiple pushes are not required the del button and the ins button use the basic insertion algorithmsthe same as those in the tree workshop applet this is how the work is divided between the applet and the userthe applet does the insertionbut it' (mostlyup to the user to make the appropriate changes to the tree to ensure the red-black rules are followed and the tree thereby becomes balanced