system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: How do QR codes work?

How are QR codes able to direct me to a website/ fill out correct information on blank fields?
gpt
QR codes are a really cool way of encoding information in an image. You'll notice of to look at one, there are a few obvious landmarks that all QR codes share, the large nested squares in 3 corners, and the smaller nested squares in the final corner. These landmarks allow the decoder to determine the scale and orientation of the QR code. 

Once that's determined, the remainder of the QR code is a lot like binary, it's a grid of squares which are either filled or unfilled, like binary 1s and 0s (this is a simplification of the actual encoding mechanism which is quite complex and allows for a bunch of redundancy, which is why you often have a company logo over the QR Code, obscuring some of the grid, but it still works) 

The decoder then reads the "binary" message from the grid, and it comes out as a URL to a website or an app, or some instructions that the reader so can act upon.