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eye gaze communication system
Technology Brief
All About 2D Bar Codes
By MICHELLE MAN
September 2007
YOU MAY NOT KNOW what they are, but chances are, you come across them on a regular basis — on your cell phone bill, airline boarding pass, and parcels delivered to your home. They’re 2D (two-dimensional) bar codes, an advanced type of bar code that can pack loads of information into a very small space, sometimes even in an area as tiny as a pinhead.
When most people think of bar codes, they think of
1D bar codes, which consist of a row of parallel vertical lines. This is the type of bar code that you will find on most retail packaging. Conversely, 2D bar codes can appear in a variety of configurations, such as a block of multiple 1D bar codes stuck on top of each other, or a swarm of dots with a bull’s-eye in the middle.

While 1D bar codes encode data in only one dimension
(horizontally), 2D bar codes encode data in two dimensions
(horizontally and vertically), enabling them to compress more information in a smaller space.

1D vs. 2D Bar Codes
A good way to think about 1D bar codes is as a printed version of the Morse code.
Instead of dashes and dots, a 1D bar code uses wide bars and narrow bars to encode information. What a bar code scanner does is analyze the wide bars, narrow bars, and spaces in between to extract the original information.
First used in retail in the 1970s, 1D bar codes have the drawback of not being very space-efficient: they get longer as more data is encoded. As a result, 2D bar codes were invented in the late 1980s as a way to encode more data into a smaller space.
While 1D bar codes encode data in only one dimension (horizontally), 2D bar codes encode data in two dimensions (horizontally and vertically), enabling them to compress more information into a smaller space. This is why 1D bar codes are also known as “linear bar codes", and 2D bar codes are also called “area bar codes".
Today, 2D bar codes are so advanced, that while a

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