Linked data is about connecting resources, ideas, and facts on the web in meaningful ways. It's a standard way of using metadata to link pieces of data that represent people, places, and names in order to automatically generate connections for the user.
When used in libraries, archives and museums, Linked data allows us to connect pieces of data that were not previously connected. For example, linked data would allow you to trace a person in a photograph on one website, to a postcard on another completely different site, to a diary on yet another one. Based on technologies of the Semantic Web, it also allows us to represent specific relationships between people, places and things, indicating, for instance, whether that person in the picture wrote the diary or was mentioned in it, whether the postcard was sent to them, written by them, or mentioned them. Enriching data through linkages allows us to connect information from different sources, resulting in increased visibility of collections and linked knowledge.