Amazon on Monday revealed that it will open a brick-and-mortar grocery store called Amazon Go, an ambitious bid by the once online-only retailer to gobble up more of Americans' shopping dollars by taking the fight more directly to traditional supermarkets and big-box stores. The store will be powered by a web of technology that allows customers to fill their shopping bags and walk out without going through a checkout process, a concept that has long been discussed in the retail industry but that has not been implemented at any major U.S. stores. The idea is that it will shave time off the shopping experience. Here's how Amazon Go will work: Customers download an app and then swipe their smartphones as they walk through the store's entrance. Then they just start picking up groceries.