It is scanned several billion times a day, it is on nearly every manufactured
product sold in a shop, and the price is not in it. It never has been.

Those thirty bars encode twelve digits. The first identifies the type of
product, the next five identify the company, the next five identify the exact
item down to the packaging size, and the last is a check digit calculated from
the other eleven so a misread cannot pass unnoticed. Nothing in there says 67
cents. The price lives in the shop's own database, which is why the same item
with the same barcode costs one thing in one store and something else three
miles away.

Leaving the price out is what made the symbol universal. Put it in the bars
and a price change means reprinting the packaging, a promotion means a
different box, and the manufacturer is setting retail prices. One printed code
could not have worked for every shop in the country.

But the hardest decision was the shape, and the design that nearly won was a
circle.

Norman Joseph Woodland drew the idea in the sand on Miami Beach in 1949. He
was thinking about Morse code, four dots and dashes, and he pulled his fingers
downward until they stretched into narrow and wide lines. Then he bent the
lines into concentric rings so the pattern could be read from any direction.
That bullseye held the patent, it had a working pilot store, and RCA was
backing it.

It lost because of what printing presses do to wet ink.

Also covered:

How a seven unit grid holds each digit, and why the same code works on a
 cereal box and a tin of anchovies
The parity trick that lets a scanner know it has read the code backwards
Why a checkout scanner aims at nothing and wins by brute force
Why the real revolution was inventory, not queue speed
26 June 1974, Troy Ohio, a ten pack of Juicy Fruit, and why that pack is in
 the Smithsonian
Why the system nearly failed in 1976
Why consumer groups and unions fought to keep price stickers on every item

#Barcode #EngineeringHistory #HowThingsWork