The DigiD (Digital Identification) is a way of providing secure access to national and local authority websites and to a growing number of other websites such as health insurers and pension funds.
The DigiD is linked to the BSN (issued upon registration at the municipality).
Application for a DigiD can be done via the DigiD website. Applicants will be prompted to choose a gebruikersnaam (username) and wachtwoord (password), and then these two codes are subsequently used to gain access to relevant websites.
The DigiD app is being used more often as method of access to websites, so it should also be requested when you apply for a DIgiD.
Once you have a DigiD you can also use it when you are not in the Netherlands, but only Dutch nationals are able to apply for a DigiD when not resident in the Netherlands.