A Link is created with a set of credentials associated to an end-user's access to an institution. For example username and password are a set of credentials used to log-in to home banking, so this credentials are used to generate a link.
To start consulting the information of your clients' accounts or your own, such as identity, transactions, balance, you must first register a link.
Recommendation
In order to simplify your integration with your clients, we recommend to use the Widget to link creation.