# Square 2D barcodes?  What are they?

**URL:** <https://boards.straightdope.com/t/square-2d-barcodes-what-are-they/387671>\
**Category:** Factual Questions\
**Created:** [January 12, 2007, 5:24am UTC](https://boards.straightdope.com/t/square-2d-barcodes-what-are-they/387671 "2007-01-12T05:24:11Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![bbs2k](https://avatars.discourse-cdn.com/v4/letter/b/e495f1/32.png) [@bbs2k](https://boards.straightdope.com/u/bbs2k)\
**Post date:** [January 12, 2007, 5:24am UTC](https://boards.straightdope.com/t/square-2d-barcodes-what-are-they/387671/1 "2007-01-12T05:24:11Z")

</div>

How do you read [this](http://technobiography.edongskey.com/wp-content/photos/2D_barcode_sample.jpg) type of square barcode? What reads it, and why do I find it in such innocuous places. It’s on my medical supplies at work, as well as the shampoo in my shower, albiet both of them very small. Can anyone give me a good skinny on this?

---

<div class="post-metadata">

**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\
**Post date:** [January 12, 2007, 5:36am UTC](https://boards.straightdope.com/t/square-2d-barcodes-what-are-they/387671/2 "2007-01-12T05:36:41Z")

</div>

It’s called [PDF417](http://www.barcodeman.com/faq/2d.php). It’s used to store a larger amount of information than a 1D barcode, like UPC or Code 39. It’s read by laser scanners, similar to ones used to read 1D barcodes and sometimes optically, using a CCD camera.

---

<div class="post-metadata">

**Author:** ![Sleel](https://avatars.discourse-cdn.com/v4/letter/s/73ab20/32.png) [@Sleel](https://boards.straightdope.com/u/Sleel)\
**Post date:** [January 12, 2007, 5:40am UTC](https://boards.straightdope.com/t/square-2d-barcodes-what-are-they/387671/3 "2007-01-12T05:40:17Z")

</div>

Looks like the kind of barcode I see all the time here that the camera on my mobile phone can recognize. Depending on what it codes for, it will direct you to a web page or input a number for you. Usually it’s for a web page.

---

<div class="post-metadata">

**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\
**Post date:** [January 12, 2007, 8:31am UTC](https://boards.straightdope.com/t/square-2d-barcodes-what-are-they/387671/4 "2007-01-12T08:31:27Z")

</div>

[QUOTE=Q.E.D.]  
It’s called [PDF417](http://www.barcodeman.com/faq/2d.php).  
[/QUOTE]  
Actually, I think the linked image is a format called [Data Matrix](http://www.jollytech.com/support/knowledge_center/barcode_symbologies/data_matrix.php).  
[PDF417](http://www.jollytech.com/support/knowledge_center/barcode_symbologies/pdf417.php) is a different symbology.