Data can be shared between pages in several ways. One option is to use components. Components are useful because a single component can be used in multiple places. If you need to change a component's content, you only need to update a single instance of it. That is, you don't have to update every page where the component occurs. However, a component isn't always the best option for sharing data. Exports provide a more programmatic approach to sharing content across pages.
Exports are user-defined attributes added to a page node in a navigation, link, taxonomy navigation, references element, or LinkSet element. The values of the export are queried and extracted from the elements or attributes within the content item that the page references.