A QR Code stands for Quick Response and it's a two-dimensional version of the Barcode that's able to convey a wide amount of information in an instant with the scan of a mobile device.
These are able to store up to 7089 digits or 4296 characters, including punctuation marks and special characters. Equally, the Code can encode words and phrases such as internet addresses. The more data is added, the more the size increases and its structure becomes more complex.
Here's an example using a link to a YouTube video which you can simply scan using the camera app on your phone.
QR codes work similarly to barcodes at the supermarket. Each QR code consists black squares and dots which represent different pieces of information. When scanned, the unique pattern on the barcode translates into human-readable data. This transaction happens in seconds.