At a grocery store, your device can scan a QR code near a product to find more information or to download a coupon which can be scanned at the checkout. This technology is in its infancy, and the promise of their usefulness will be fulfilled by the ease of use to the consumer, and the relevance of marketeres.
In our grocery store example, the manufacturer can vary the offer of the coupon by daypart, day of week, or other variables (geography, say). On big shopping days (Saturday), the....