These days, convenience is held mostly above all else. We can access a vast portion of the world's knowledge from our pockets, for example. The quickest way to get to some of that knowledge, as well as more interactive content like games and shopping, is by scanning QR codes in the real world. Found on posters, store shelves, and tons of other places, the two-dimensional square bar codes never managed to truly go mainstream, but they're still used quite widely, and are much quicker and easier than Googling a show coming to town or searching Twitter for a profile to follow. In the case of the latter, Twitter is embracing the QR code to make it a bit easier with the latest beta update.
It's deceptively simple and opens up more than a few new opportunities for Twitter power users to get themselves out there by leaving their calling card around in the real world. Likewise, meeting somebody face to face and forgetting their name or handle will be a thing of the past, since they can show you their QR code and you can use it to follow them instantly. Every single Twitter user gets one, not just verified users, celebrities, and the like, meaning that anybody who's creative enough can take advantage of the move. It also means that profiles hand-made for events, causes, and the like can be advertised around town with a QR code that interested users can scan to follow the profile and get more info and updates.
To get their camera going and scan a QR code, all a user has to do is slide out the navigation drawer. From the camera, a user can simply center a QR code they find in the wild, or tap a button to reveal their own QR code for somebody else to scan. You can also import codes that you've taken pictures of outside of the app from your gallery. If you pull up your own code, you can also share it around, allowing you to spread it to others virtually even more easily than in the real world. The feature is only in the beta version for now, but given its polished state, will likely be in the next stable version of the app.