What Is a QR Code? 

After lunch, mom was resting and my dad was busy in the study room. Daniel was lying on a bamboo bed and let his mind wander. After a while, he got thirsty and fetch a beverage from the refrigerator. Then he lay down on the bed again, put the cold beverage bottle on his forehead, closed his eyes and thought about how to ask mom’s permission to go camping. Suddenly the bottle slid down his nose. Daniel was so frightened that he opened his eyes at once and saw there was a maze-like image on the label of the bottle.

He sat up and looked at it carefully. There was a square pattern with black-and-white dots on the label. It didn’t look like a maze and there was a note under it: scan it to get a surprise! He thought it was similar to the scratch-off layer on beverage bottles he had bought before, so he scratched it with his fingers. But the pattern remained the same. Daniel felt cheated by the beverage manufacturer and took a gulp. Then he got really bored and fell asleep.

Somehow, mom and dad quarreled in the study room, and their voices woke Daniel up. Daniel turned over and his back was poked by the beverage bottle. He felt that the feeling of being cheated was really bad. So he stopped sleeping and ran to the study room. It turned out that mom and dad were hanging a painting on the wall, a Chinese painting that didn’t look good, with only several black brushstrokes. Daniel went to his mom and said, "Mom, don’t buy this kind of beverage any more. I was cheated by it."

Mom was surprised at what Daniel said. So Daniel told about what had happened and how he scratched the pattern, making both his mom and dad laughed. Dad laughed for a while and said, "You misunderstood. That’s not the fault of beverage manufacturer. The pattern is a QR code. You have to scan it with your phone camera, instead of your fingers."

Daniel asked confusedly, 'Dad, are these black and white dots QR codes? What is QR code?'

Dad handed the painting to mom and turned to Daniel and said, "The black and white dots on the QR code represent the numbers 0 and 1 of the computer. You know, computers store data in binary. That is, no matter what the data is, a picture or a song, it’s a long sequence composed of multiple 0 and 1 in the computer, and differently arranged black and white dots in QR codes. Assuming that the white dot represents 1 and the black dot represents 0, then the data can be transformed into a QR code.”

Daniel understood a little, but was still confused and asked, But why so troublesome? Those data saved in the computer well, why transform them into black and white dots?

Feeling as if he had missed something, dad added, "Data can be easily identified after such a transformation. It is mainly used in real-time services. For example, if you go to a store to buy something, you can pay with the QR code. And you don’t want to wait for a few dozen minutes to pay, right? The QR code can be recognized quickly by the camera."

Mom turned around and said, "Last time we went to a supermarket, I paid with my mobile phone. You probably didn’t notice that. The QR code was invented by the Japanese in 1994. It has high fault-tolerant function. For example, a QR code with a small corner damaged can also be identified correctly."

Daniel understood finally and thought about to go shopping someday and try the QR code payment.

Author: Huang Jing