Programmers, when first learning their trade, spend a few weeks or months working on the basics - the syntax of the language, how to work with strings and numbers, how to assign variables, and how to create basic functions. About this time, they also encounter two of their first data structures: lists and dictionaries. Lists can be surprisingly complex structures, but in most cases, they consist of sequences of items with pointers (or links) from one item to the next. While navigation can be handled by traversing the linked list (also known as an array), most often this is shortcircuited by passing in a numeric index that can be given from 0 (or 1 in some languages) to the position of whatever item is required. A similar structure is known as a dictionary.