How to tell the authenticity of Nike, Adi and other bags?

YKK's method is no longer feasible. I have a small house that says YKK! First of all, we should look at the workmanship of the bag and compare the technical details, such as zipper and sewing. It's best not to risk buying the ones on Taobao, saying that they are genuine foreign trade, but they are all high imitation and deceptive; The safest way is to get it to the store and ask the clerk to help you identify it.