A square barcode that stores information and can be scanned with a smartphone camera. Like a digital business card that contains links, contact info, or other data.
Restaurants use QR codes on tables that you scan with your phone camera to instantly view their menu online.
A QR Code is a data format (2D barcode), not a cloud service. Cloud providers don’t offer a direct “QR Code service,” but you can generate QR codes in applications running on any cloud and store/serve the linked content using cloud storage, databases, and web hosting.