When I began working with the octothorpe as a “finalist” for the Barthle Tax and Accounting logo design, my daughter suggested that I look into the fascinating history of the symbol. I “wiki’ed” it but she went one step further and sent me this link to Roman Mars 99% Invisible podcast on the subject.

I would like to share three fascinating octothorpe facts with readers that are highlighted in the 99% Invisible episode 145. Please listen to the entire podcast.

1. As a “hashtag” on twitter: The symbol earned its name because the British called it a hash mark. In the world outside of Twitter, though, it is still “the number sign.” It has a lot of other uses, too. In chess, it represents a move that results in checkmate. In proofreading, it means a space should be inserted. On Swedish maps, it represents a lumber yard.

2. In 1968, Bell Labs  they decided to add keys on either side of the zero. This would make the keypad into a nice even rectangle, and give users a few more options on a phone menu.They settled on the asterisk (*) and the number, or pound sign (#), mostly because they were symbols that they knew computers would be able to recognize and were already on the standard QWERTY keyboard.

3.  In October of 2007, a developer named Nate Ritter was reporting on a wildfire in San Diego, and Ritter was using Twitter to post updates as the story developed. He began related tweets with, “San Diego Fire.” Chris Messina reached out to Nate Ritter and proposed that he use “#sandiegofire.” Then other people looking to find out about the fire would know exactly where to look on Twitter.

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