Your date of birth is one part of the required information needed for most domain registrars or administrators. This information is used to verify your identity in case there are any problems with the domain. For important changes with domains (such as transferring ownership), generally a notarized signature is needed and because of that it’s important to fill in all the required information correctly. Doing so will help you avoid any trouble during domain changes or renewal.
Webnode also offers so-called "private registrations". With private registrations, no personal information provided during the domain registration is displayed on the Internet, though it is still required to fill in your contact information for domain registration so we can confirm who the true domain owner is.