'We won't need to bother inputting numbers and e-mails into our smartphones anymore,' said Simon So Wing-wah, an assistant professor in information technology at the Hong Kong Institute of Education. 'All you need to do is scan the QR code, which will display the contact details on the smartphone, and you can decide to save it or not.'

Compared to standard barcodes, they store a lot more information. The design allows characters to be stored in a format where the data is not identified by a single vertical black strip. Instead, characters can be placed anywhere within a rectangle - with the information stored in both the horizontal and vertical directions.

As with barcodes, there are a bevy of different two-dimensional codes such as Colour Code, EZcode, Aztec Code, Bullseye, MaxiCode, 3-DI, Shot Code and SemaCode out of around 40, but QR is the most commonly used.

But 'the penny hasn't dropped in Hong Kong yet', according to Andre Meyer, director of consultant firm Cloud Solutions and a QR code expert, who advises businesses on how to tap into the boundless potential of using QR codes.

'QR codes are becoming more visible,' he said. 'But the reason they may fail is that there is no benefit for the user when they scan the code.

'With MTR advertisements, the QR code usually just brings the user to a website that is not even designed for a smartphone. If businesses abuse them, the experience of the consumer will be poor and people will just ignore them.'

He draws the example of a client who is a wine distributor to various restaurants, but could not gather information on the diners who order the wine in the restaurants. Meyer suggested placing a QR code onto the wine list that can offer information to the customer, such as food to pair with the wine or discounts on wine clubs. And in return, the customer is asked if they will agree to share their location and other personal details.

'What the QR code has allowed is for businesses to get closer to their customers,' said Meyer. 'The code is literally a paper bookmark, and the idea is you can use your phone to scan the bookmark and be delivered to online content on your phone.'

Meyer said people with smartphones tended to be between 20 and 50. 'So there is no point in having QR codes when you are trying to sell retirement plans.' He said the QR codes could fit seamlessly into our everyday lives. 'When you send out wedding invitations, you can simply scan the QR code, and the bride and groom are actually inviting you personally through a video,' he said. 'And in other countries, you have QR codes on gravestones, where people can learn about a person's life through videos and slideshows.'

And in a city where property is king, Meyer has a winning idea for estate agents. 'Instead of having pieces of paper stuck on the window with information on size and price, you can have a QR code that will let you tour the whole apartment - all before you call the real-estate agent for a visit.'

Although QR codes seem to be the prevalent choice for many marketers now, the fact that the information stored could not be modified might mean it would one day make way for newer technology, said Dr Chu Lap-keung, who is an expert in supply-chain management and a lecturer at the University of Hong Kong's department of industrial and manufacturing systems engineering.

'Data is fixed in a barcode or QR code, but in radio-frequency identification, or RFID, a lot more data can be stored, and it is programmable.'

The technology enables the tracking of products as they go through the entire production and supply chain, up to the point of sale.

Unlike barcodes and QR codes, which only work a very short distance from the user, RFID tags work from several metres away.

RFID tags were used at technology-conscious companies such as Apple and Wal-Mart, he said. But they are a small minority, and many companies are finding the technology too expensive.

'The tag itself is expensive, and the scanners and other facilities it needs are different from those applicable to barcodes and QR codes. So I think it's possible that RFID may one day take QR codes' place, but it's a slow process. The inertia is very big,' Chu said.