This is the country-code top level domain from Finland.
When .FI domains are registered through us, we will require an identification number the same that will be sent along with the domain registration request. This number may vary depending on your current situation:
If you are an individual located in Finland a valid Finnish Identity Number is required.
If you are registering this domain under a Finnish Organization, an Official Organization Number is required.
For individuals outside Finland, the personal date of birth is required.