A linked list is a simple data structure, as shown earlier in Figure 6.1, that allows you to maintain an ordered list of items without having to know ahead of time how many items you’ll be adding. To build this data structure, you need two class modules: one for the list head and another for the items in the list. The example presented here is a sorted linked list. As you enter items into the list, the code finds the correct place to insert them and adjusts the links around the new nodes accordingly.