What would be the best way for one to add categories to a Gui frame?

My main goal is to have a list act like a category system. When you add a label to the list, it filters it into the correct category, and when you click an arrow next to the category, it hides all of the labels in that category. Example, when you close a category in the explorer, it shows the category label but not the items, however if you expand it back out, all the items are show. What would be the best way to do that? (Not asking for a script, merely just a method or process one should use.)