Iteration is the act of repeating a process with the aim of approaching a desired goal, target or result. Each repetition of the process is also called an "iteration", and the results of one iteration are used as the starting point for the next iteration. The pentagon on the right also is a good example of how iteration relates to recursion. Although iteration is used, for example, to parse a linked list, recursion is required when we step up to binary trees. The pentagon demonstrates both.