The Value Added Tax, or VAT, is a general tax that applies, in principle, to all commercial activities involving the production and distribution of goods and the provision of services. In order to open a shop with us you need to be registered for VAT and have a VAT number. We need your VAT number in order to know how we should tax you.
When you register for VAT you will be given a VAT number. The format of the number depends on the country you register in but starts with the country code, here you can see the different formats for all EU countries. It's important that you provide the correct VAT number, especially in trade with other EU countries.
You can find the link to the correct national tax authority here.