Shared links are URLs that are generated for files or folders stored in Box, which provide direct, read-only access to the resource.
Shared links which are set to an open access level allow anyone with the URL to access the item, while shared links with company or collaborators access levels may only be accessed by appropriate authenticated Box users. See here for all of the options and admin settings related to shared links.
Users can access shared items by entering the shared link URL in a browser. Applications can also access shared items using the Shared Item API.