VAT is the replacement for the purchase tax ( = sales tax) we had before, it is a tax added to the value of the item.
VAT must be included in the price displayed for consumers, for trade/wholesale it is optional and usually excluded and a separate tax amount shown on the price sticker along with the rate at which it is charged at. In the UK there are 3 rates of VAT:
Standard VAT rate: 20%
Reduced VAT rates: 5% property renovations
Reduced VAT rates: 0% foodstuffs, books, pharmaceuticals, medical, passenger transport, newspapers, childrens clothing
The only way of really avoiding the VAT is to export the item to a country that is outside the European Economic Area
Lots of info here
http://www.vatlive.com/