A value added tax identification number or VAT identification number is an identifier used in many countries, including the countries of the European Union, for value added tax purposes. You can find more information on the EU website, here: VAT Identification Number
Note: Providing your company’s VAT identification number in the assessment is optional.
The Data Universal Numbering System (D-U-N-S or DUNS) is a proprietary system developed and managed by Dun & Bradstreet. It assigns a unique nine-digit identifier—called a D-U-N-S Number—to a single business entity. This number is widely used for identifying companies globally and verifying business information. You can learn more about the D-U-N-S Number on Dun & Bradstreet’s official website: https://www.dnb.com/en-us/smb/duns/what-is-a-duns-number.html