A hub is integrates data across any number of data providers. Hubs are pre-configured to retrieve data from a few public data providers, but individual users can link additional data providers, which could be either public or private. To do this, the hub provides a Subscription interface, accessed via the Subscribe tab, where the hub will display a list of active providers and a form whereby new subscriptions can be entered. To subscribe to a new provider a user enters the URL for the provider interface for the data provider to subscribe to.