Value Added Tax (VAT) is used throughout Europe as a form of sales tax. Visitors from the United States who shop in Europe may be entitled to a substantial refund of VAT once they leave Europe. Since VAT can be fairly hefty, the refunds are well worth asking for.
VAT refund rules vary from country to country, and depend on the amount spent, and the type of purchases. Refunds for VAT taxes on merchandise are generally more readily available than refunds for services.
Some paperwork is involved, which also can vary from one country to the next. Paperwork has to be presented at Customs as the traveller leaves Europe. Some stores, such as Harrod's in the UK, have special courtesy desks that will assist customers with all needed paperwork.
The Resources section has additional details on how to get your VAT refunds after your European shopping spree.