In original or originally restored condition antiques are very valuable and are usually either protected and stored or exhibited in car shows but are very rarely driven. Some consider such old cars for sale be a form of investment. Buying a particular antique car is then done primarily in view of profit in a future sale and not of enjoying a drive or taking pleasure in restoration work. The market for antique cars fluctuates wildly over the years. There have been periods, like the 1980s, which have seen strong and continued increase in price, but other periods which saw precipitous declines. A vintage car is commonly defined as a car built between the start of 1919 and the end of 1930 known as the "Vintage era". There is little debate about the start date of the vintage period but the end date is a matter of a little more debate. The British definition is strict about 1930 being the cut-off, and is widely accepted while some American sources prefer 1925 since it is the pre-classic car period as defined by the Classic Car Club of America. Others see the classic period as overlapping the vintage period, especially since the vintage designation covers all vehicles produced in the period while the official classic definition does not, only including high-end vehicles of the period. Some consider the start of World War II to be the end date of the vintage period. Either way they are both in the category of old cars for sale.