Scan a QR code every day and never once think about those three squares. I was in that category for years. Turns out they are doing some genuinely clever engineering work — and the reason there are exactly three, not four, is more interesting than you’d expect.
They Have a Name: Finder Patterns The three large squares are officially called position detection patterns, though almost everyone calls them finder patterns [4]. They sit in the top-left, top-right, and bottom-left corners of every QR code — never the bottom-right. That asymmetry is intentional, and it’s the whole point.