I'll use the analogy of bread baking. The French are master bread bakers and take their bread very seriously. Some American sourdoughs and supermarket breads call their products "French" bread. They use the term because the bread is crusty or shaped similarly to traditional French breads. But calling all stranded color knitting Fair Isle knitting is more like calling a Jewish challah or Indian naan a "French" bread.
Fair Isle is the southernmost island in the Shetland Islands and is between Norway and Scotland. In the distinctive style of Fair Isle knitting the foreground and/or background colors often change in a single pattern chart. This usually doesn't happen in other types of stranded color knitting. (An exception is the cover purse on Andean Folk Knits, where the foreground color changes from red to orange to green.)
Fair Isle:
Not Fair Isle (Latvian):
Fair Isle:
Not Fair Isle (Norwegian):
Fair Isle:
Not Fair Isle (Peruvian):
