Hi Marc, 

Thanks for the question.

The use of QR codes is extremely popular in China, much more popular than that in the US, as I observed in the past two month in Hawaii.

I attribute the the prevalence of QR codes in China to the widespread use of WeChat, THE MOST POPULAR instant messaging app in mainland China (for more information, read: http://a16z.com/2015/08/06/wechat-china-mobile-first/). 

The QR codes are widely used in three types of scenarios:

First, QR code as an business card. People scan others' identification QR code generated by WeChat to add them into the contacts list. Many people now print their WeChat identification QR codes on their business card, so that others could scan it with their phone to get connected. It's similar to that people ask to become Facebook friends in the US, but it is more easy and convenient - one don't need to type the other person's name and search for the right person.

Second, QR code as a portal to various services. Many QR codes link to WeChat subscription accounts which are run by individual as a personal blog, by organizations to communicate information, or by news outlets as a channel to spread their media products. Many other QR codes link to external websites, and they could be advertisement of a company, link to the download page of an app, or information about an activity and so on.

As the active users of WeChat in China has exceeded 500 million in 2014, the huge networks on WeChat has attracted numerous companies, organizations as well as individuals to exploit its potential business value, and the QR code is seen as an ideal portal of implementing O2O (online-to-offline) services. 

Third, QR code as a link to third-party payment processors. The prosperous e-commerce in China has prompted a wide use of third-party payment, THE DOMINANT ONE is Alipay provided by NASDAQ listed company Alibaba, as traditional banks failed in providing easy-to-use online payment service.

As more and more people are using  smartphones, Alipay has partnered with many vendors to streamline the payment process - customer could pay the money by simply scanning the QR code generated by the vendors with the Alipay apps installed on their smartphone, and then the payment is processed through your Alipay account and money is transferred to the vendor.

Hope this answers your question.

Yi

I've had experiences where I didn't even notice a QR code because it was placed in a location that I wouldn't necessarily associate with having one. For example, I was either in the Seattle or Spokane airport where there was a campaign to conserve water and paper towels when using the restroom. There was a QR code placed on a paper towel dispenser which I completely overlooked until a child pointed to it and asked what it was. Above the QR code read something along the lines of "How are we doing?" which I assume referred to how effective restroom users believed their campaign was. In a place such as an airport restroom, people are in such a transitory state of mind that they wouldn't notice or even care to scan a QR code.

From reading Yi's answer, it sounds like China uses QR codes in much more effectively. Rather than using QR codes to suggest further work for a user (such as directing them to a survey), it sounds like in China, QR codes are more catered to the users/scanners needs. 

I personally won't use a QR code if, from looking at the external characteristics of where the code is placed, I believe it's not worthwhile to scan. Same goes if I'm in a museum. I may only scan QR codes of the pieces that are of particular interest to me. I guess this plays into perceived affordances of any kind of mobile storytelling device. 

One social media app that uses QR codes effectively is snapchat. Each user is assigned a QR code when signing up for a snapchat account. Using the camera capabilities of the app itself, users scan these QR codes to add each other seamlessly. 

YIKES! I've had both excellent and terrible experiences with QR codes. I'll share the funnier of the two experiences. When I was working for a tour company, they were desperate to get viewers to their website and social media pages. Their audience (their customers) were mainly in the 60+ range. The advertising manager was persistent that QR codes were the way to go, this was about 2 years ago. I tried to explain that the technology was still working out a lot of kinks related to QR codes so maybe we should wait on using QR codes as a way to attract our customers to our website. After many conversations, the advertising manager convinced the president of the company to create QR code lei. NO, I'm not joking. She created a sample, that looked a bit strange. Let's just say that the QR codes were not the issue at that point. 

We ended up putting the QR codes on all of the vehicles that would tour the island so that customers on tour could visit our website if they scanned the code, but also those who saw the code and were intrigued. The issue we ran into was that people had to download another app on their phone in order to actually have the QR code produce the content. 

QR codes are something I'm on the fence about, but I think were an excellent invention! 

Interesting to hear all of these experiences with QR codes; I like the idea of using them on business cards, which makes great sense, since the paper product is sort of the point of that. I also have ran into the download issue, in which you have to have a QR code reader on the phone to make these work; while that's not difficult to accomplish, and then use, it still is one more step, and for me, it's always sort of a pain to find my QR code reader among all of my apps, because I just don't use it that much. If the QR code reader is integrated into another app, that is helpful. ... I also found it frustrating when QR codes are printed and left around in public places, and then they will have a dead link or just not work properly, which also affects my opinion of that person or group's ethos, especially tech ethos. 

By the way, a similar question has been asked here: https://www.researchgate.net/post/Can_you_think_of_any_ways_that_the_use_of_QR_codes_has_enhanced_your_experience_of_a_place