VAT stands for "Value Added Tax", which is an indirect sales tax. If you live in the European Union (but outside of France, Germany or the UK) and are exempt from VAT, then you can fill in your VAT-ID (VAT No.) into the appropriate field of your account. You need to be registered as a business customer in order to be able to use this option. Before finalizing the order process the German VAT will be deducted from the sales price to avoid double taxation. Please make sure that you are actually exempted from VAT for purchases in the EU before you fill in your tax ID, otherwise please ignore the optional field for the VAT-ID.