Globalization certainly has its advantages. Anyone can order almost anything online with a few clicks and have it conveniently delivered to their door regardless of where it is. However, convenience aside, many consumers purchasing things like cameras and lenses may unwittingly be purchasing gray market products rather than "legitimate" ones.
An unfortunate couple in Chicago learned how camera manufacturers treat what is known as "gray market" equipment when Nikon refused to service their P1000 camera. They were confused, as they didn't buy it from a shady, unknown site, but from Walmart: an authorized Nikon dealer.
So-called "gray market" products are popular in the world of photography, but buying your Sigma gear through an unauthorized reseller will cost you in the long run. Not only will Sigma not honor the warranty on gray market products, they'll actually charge you extra to fix them.
Canon USA has filed lawsuits against a number of camera gear retailers in an attempt to stop the sale of gray market camera gear. The gray market is when a dealer imports and sells unauthorized gear that was intended for another country's camera market. The cheaper gear is legitimate, not counterfeit, but it's unauthorized and usually isn't covered by Canon's warranty.
So, the Nikon D7000 I bought, brand new in early 2014, is a fake. Unbeknownst to me until very recently, of course. Let's start at the beginning -- it being the most logical and traditional place to start.