RM: This is 99% Invisible, I’m Roman Mars.

RM: Every morning, I wake up, roll over, pick up my phone, and check Twitter. I’m not proud of this, it’s just the way it is. Twitter always struck me as the social media platform that was the most like broadcasting. It’s an ongoing low boil conversation you jump in to get a sense of what’s going on in the world, and jump out. It’s a lot like scanning through a radio dial, but it’s mainly comprised of people you know, and the people they know, telling you about their day, reacting to shocking news, making jokes, and sending around links. I tweet at @romanmars by the way.

AT: And sometimes I tweet at @trufelman.

RM: Because this producer’s name is Avery Trufelman.

AT: But if you want to find out about the show in general, there’s a hashtag for it. It’s #99pi. And there’s also #AIGAdesign for this conference!

RM: The hashtag of course, is two vertical lines intersecting two horizontal lines – it looks like a tic-tac-toe board.

AT: In the current digital world, the hashtag identifies movements, events, happenings, brands, topics of all kinds. Hashtags help people gather.

CM: That’s incredible power to give to like, individuals and as a character, I mean, awesome; it’s got like this little typographical superhero story now.

RM: And this superhero story, stars Chris Messina.

CM: I’m Chris Messina, the inventor of the hashtag. I’m a designer, and translator.
(int ape)AT: Translator?
CM: Of human culture. That’s probably a little bit bloated, I dunno. I dunno what I do.

AT: Chris was the first one to use a hashtag on Twitter. Before it was even called the hashtag.

RM: Back in August of 2007, when he was going to an event called BarCamp.

CM: It’s a nerdy thing, it’s a totally nerdy thing. It’s uh, it’s uh, an event that you go to that’s completely unstructured and unplanned, and the participants figure it out.

AT: So the participants needed a way of organizing, which led Chris to tweet the very first hashtag; even though at that point it was just a pound sign.

CM: How do you guys feel about using pound BarCamp for groups?

RM: Putting a pound sign in front of the word BarCamp helps the other people at Bar Camp, pick out the word BarCamp in their twitter stream, and encourages all the other BarCamp participants to use the word BarCamp in their tweets. So now everyone who’s interested in BarCamp, can search for that term and join the conversation. Now let’s hope I never have to use the word BarCamp again.

AT: So some people got on board, and agreed to use the pound sign. But most were like, “Okay, you go do that.”

RM: The pound symbol had already pervaded other corners of the web. Internet Relay Chat, AKA, IRC, used the pound sign to represent chat rooms, or conversation channels.

CM: There was another social network at the time called Jaiku, that also had these channels. So, there was other stuff that came before me.

AT: But Chris was using bunches of pound signs throughout his tweets.

CM: I was putting pound symbols in front of my words, and people were like, “I don’t understand what you’re doing. You’re putting all this strange punctuation in front of your stuff, and it looks dumb.”

AT: But the true believers stood by the sign. One twitter user called it a Hash Tag, because hash is the British name for the sign, and these were being used as category tags.

RM: And then the hash and the tag got conjoined into one word.

AT: Chris actually brought the hashtag idea to Twitter headquarters directly, but they thought it would never catch on, it looked clunky.

RM: Then a few months later, in October of 2007 the purpose of the hashtag was fully realized.

CM: A friend of mine was down in San Diego, his name is Nate Ritter, and he was using Twitter basically pulling all this stuff together around these fires that were going on in San Diego.

RM: Wildfires were raging around San Diego, and residents were tracking the spread through Nate Ritter’s tweets.

CM: But he was prefixing all his tweets with San_Diego_Fire.

AT: So Chris told Nate that he should switch to #SanDiegoFire all one word. And then other users would imitate him. And it worked. People trying to find out about the fire knew exactly where to look on Twitter. And this was the moment where everyone went, “Oooooooooh, that what these signs are for.”

RM: Now to clarify, Hashtags weren’t a thing that Twitter planned on. And they kind of dragged their feet on incorporating it.

AL: We kept thinking, “There must be a better way to organize all this information that’s falling through Twitter.” We kept looking for it and we never really found it. But the Hashtag in retrospect is just this obvious tool.

AT: Andy Lorick, then an employee at Twitter, officially brought in the hashtag.

AL: The users brought in the Hashtag. Look, all I did was link the Hashtag to Twitter search. One line of code, it took me about 15 seconds, didn’t really ask anybody.

AT: That one line of code meant that when you clicked on a word with a Hashtag in front of it, you’d see a page with all the other tweets that also contained that hashtagged word. And basically this helped you round up everyone who’s talking about a specific topic.

RM: And now the Hashtag is a tool used in advertisements, social movements, music videos, memes, tv shows…

AT: It’s getting to the point where the hashtag is erasing the symbols other uses.

CM: A friend of mine actually sent me a tweet the other day saying that his delivery guy showed up and said he was looking for Hashtag 2A.

RM: Though I’d hope that most people who make that make deliveries for a living #SMH would know it more as a number sign.

KH: In the states, it’s usually called the number sign or the pound sign. In the UK it’s often called the Hash Mark, I think more because of the way it looks than anything else.

AT: This is Keith Huston. He’s the author of a book called Shady Characters, The Secret Life of Punctuation, Symbols, and other Typographical Marks. It’s got a whole chapter on this symbol.

KH: And it has a lot of other random uses as well. It’s used in Chess to represent a move that results in Check Mate. In proofreading, if you see a hash symbol, this means “a space should be inserted here.” It’s used on Swedish maps to mean “A Lumberyard.”

RM: Hash, Pound, Number sign, Lumberyard. Whatever you wanna call it, however you want to use it, The symbol traces back to ancient Rome.

KH: So in Rome, the term Libra Pondo meant Pound & Weight. So the word Libra, like the constellation means “scales” or “balances” and Pondo comes from the verb Pendere which means “to weigh.”

AT: Libra Pondo. And these two names were interchangeable, so Romans referred to this weight measurement as a Libra, or a Pondo.

KH: So the word “Libra” was often abbreviated as LB.

AT: Lowercase l, lowercase b. Which of course, we still use.

KH: So if you see 5 lb, you mean 5 Libra or 5 Pounds in the Latin sense.

RM: This is also why British currency, The Pound is represented by a stylized L, for Libra.

AT: So, the abbreviation lb becomes a thing, and often times, it was drawn with a little bar across the tops of both letters, just to show that the L and the B were connected.

KH: Scribes, or writers got a bit careless, so they’d write faster and faster and faster, so you join the l to the b and maybe the pen doesn’t leave the paper before it does the little bar across the top. And so this seems to have given rise to the pound symbol.

RM: Or hash mark, or Lumberyard

At: Over time the symbols meaning started to bifurcate. It was used like lb for the unit pound, and it also started to be used as a number sign. It had a lot of various uses.

KH: But it was important enough to wind up on typewriter keyboards. Which is kind of the key thing, the thing that a symbol had to do in order to survive.

RM: Because symbols that didn’t make it onto the typewriter keyboard got pretty unpopular. Like the Interrobang or the Pilcrow, or the Manicule…. Poor things.

AT: Fast forward to 1963. The invention of the touch tone telephone.

(Hi, this is the Bell Systems new touch tone dial)

AT: The touch tone phone used buttons, instead of a rotary wheel. So unlike previous phones, the numbers didn’t have to be arranged in a circle on the dial anymore.

AT (continues): Bell Laboratories, a research subsidiary of AT&T experimented with a few different designs for the telephone keypad. They tried arranging the numbers in two rows of five, in a circle, in a cross, in a step pattern, but they ended up arranging the numbers 1-9 in a 3×3 grid; and then put zero alone in the bottom center.

RM: Years later, in 1968 they figured, “why not add keys to either side of the zero?” This would make the keypad into a nice, even rectangle, and give users a few more options on the phone menu.

(To repeat these options, press the star key)

AT: Because unlike rotary phones, touch tone phones allow you to continue to dial after the connection has been made. So you can punch in extensions, and navigate automated menus.

(for something information, press 1. For all other questions, press 2)

AT: Originally, Bell Labs wanted pretty shapes on the two extra buttons. They had made prototype phone that had a 5 pointed star and a diamond on either side of the zero.

RM: But an engineer named Doug Kerr would have none of this diamond and 5 point star business.

DK: Because by that time, a new thing had come into the picture. The possibility of customers dialing directly from their phones into a computer for such things as checking bank balances or validating their credit cards, or what have you.

AT: Doug Kerr wanted to make sure that the two new symbols would be one a computer could recognize. Ones that appear on a keyboard and were part of the computer’s vocabulary.

DK: So there would be no uncertainty about how a certain button would be recorded in the data that went into the computer.

RM: Bell Labs was pretty set on their star and diamond idea. So the compromise was an asterisk for the star, and a pound for the diamond. Because you know, the center kinda looked, diamond-like I guess?

AT: And for a second AT&T was like, “Can we at least call it a diamond?”

DK: There’s no reasonable reason to call that symbol a diamond. It’s not a diamond at all!

RM: AT&T didn’t know what to call this button in their manuals. And this led to the creation of what some people, including Keith Huston, consider the symbol’s official name.

KH: The Octothorpe.

RM: The Octothorpe.

LA: One day I was out with my engineering partner, and we got to talking about it and thought maybe we should come up with a new name.

AT: This is Lauren Asplund. He worked in Marketing for AT&T during that time. He and his engineering partner looked at the symbol, and saw that it had eight lines sticking out of it.

LA: So we put the word Octo in there, and then just out of thin air we said, “Well, we’ll put the word Therp, t-h-e-r-p in there too, because that sounds kind of Greek-ish and gave it some stature.”

RM: They called the an Octotherp, but that morphed into Octothorpe, which rumor has it, came about because someone at Bell Labs changed the name to turn it into a tribute to Olympic athlete, Jim Thorpe; but no one really knows.

DK: Gee, is it proper to spell it Octothorpe, rather than therp? There is no proper.

AT: Doug calls it an Oct-uh-therp, Lauren calls it an Oct-O-therp, but Oct-O-thorpe seems to have the most widespread use. Though it’s use is not widely spread.

RM: And originally the only reason Octothorpe ever caught on within Bell Labs was because the engineers thought it was a funny joke.

AT: The manufacturer, Western Electric, totally hated that name, and pretty much killed it in the 70’s. But today, for a lot of type aficionados, Octothorpe is the sign’s real name.

KH: In typographic books. Octothorpe is the name used. You might think of it as a technical term.

RM: Typographic nerds like Keith love it because it feels the most neutral and official.

AT: But in choosing this symbol, whatever it’s called, Doug Kerr and the other Bell Labs engineers really understood that we would be using telephones to communicate with computers, and this is exactly the same reason why Chris Messina chose to use this symbol back in that tweet in 2007.

CM: At the time, we had Blackberrys. We had Nokia phones, and these are hardware based keyboards. But we need something that works in the mobile world, and we need something that works over SMS because that’s the way that I’m gonna be publishing to Twitter.

RM: Which left Chris only two choices: a star, or the pound.
CM: A pound symbol or the Octothorpe, whatever. It’s probably one of the most dense symbols. And so, when you’re reading a sentence, or you’re reading a tweet, it stands out.

RM: And so you see hashtags on billboards, on promotional materials, on other social media platforms, on protest signs, It’s in front of words all over the place.

AT: But in the future hashtags are probably going to look strange and outdated. Like all the “stops” in a telegram

(telegram reads)

RM: In a telegram, as on Twitter, our speech changed, to accommodate the machines.

CM: The hashtag is a way of changing our language, to be more computer friendly. And what we’re needing to do is actually invert the paradigm where the computers become more friendly to humans.

AT: So we’re probably not going to be using hashtags the way Twitter uses hashtags forever, but this won’t mean the end of the symbol itself.

RM: It started down on paper, but then it leaped to typewriters, computers and phones, and it seems like it’s probably going to stick around, whatever we decide to call it, and however we decide to use it. Hashtag Octothorpe, Hashtag Octotherp, Hashtag Pound, Hashtag Number sign, Hashtag Lumberyard, Hashtag Tic-tac-toe, Hashtag musical sharp if you’re really lazy…




Producer Avery Trufelman spoke with Chris Messina, inventor of the hashtag; Andy Lorek, a former employee of Twitter; Keith Houston, the author of Shady Characters: The Secret Life of Punctuation, Symbols, and Other Typographical Marks; Doug Kerr, the engineer who chose the # symbol for the telephone keypad; and Lauren Asplund, who coined the word “octotherp” for AT&T.

Read Doug Kerr’s in-depth account of the octotherp story here.


Our pals at Slack are reclaiming the IRC meaning of the hash mark, as a marker for conversation channels.


“Sanza Nocturne” – Francis Bebey
“2 Ton” – Ursula Bogner
“Barfuss Durch Gras” – Hauschka
“Bubbles in the Forest” – Lullatone
“Chaos” – Geinoh Yamashirogumi
“Cracking the Code” – Keegan Dewitt
“Africa Sanza” – Francis Bebey; Melodium
“Eye Candy Bath” – Kelpe
“You Can’t Help Me” – Melodium

  1. John Marinus

    wow never mind all this hashtag tag business. All very interesting, but Doug Kerr, that’s the guy responsible for the caps lock? man i hTE THAT GUY

  2. Matt L.

    I heard a clip of “Century 21 Calling” in the show! I think someone’s a MST3K fan.

  3. Steve

    That was a great episode — it’s those type of episodes that made me fall in love with this show.

  4. andrew ensslen

    According to the Bank of England, the Pound symbol £ does not originate from the letter L as stated in your episode, but is derived from the Greek letter Sigma Σ which is the mathematical symbol for sum. As in ‘the bank of England promises to pay the bearer of this note the sum of 20 pounds sterling’ or Σ20. Σ20 became £20 as it was easier to write.

    1. Hi Andrew – I was convinced of the “L” for “libra” derivation by an old copy of Moll Flanders, in which Moll was said to be in possession of “700 L. by me in Money, besides Cloaths, Rings, some Plate, and two gold Watches.” Also, “pounds, shillings and pence” has historically (and unfortunately) been abbreviated to “L.s.d.”.

      Still, though, the sigma theory is intriguing! I’ve never heard of that derivation for “£” before. Can you point me towards a source?

  5. Roman,

    As a on again/off again Community Manager, easily one of my favorite (and that’s saying a lot given the high regard I have for all your episodes) and most entertaining #99PI’s in a while! Long live the #Octothorpe!

  6. Auros

    I’m still a little confused as to why we get an illustration about Pilcrow, which probably descends from a mark derived from C (for “capitulum”, chapter), and is totally unrelated to the ℔ mark that eventually turned into #.

    1. roman

      We make mention of the Pilcrow in the audio piece, but you’re right- it was confusing in the blog post. We’ve deleted it. Thanks!

    2. Auros

      Oh, I see. :-)

      I haven’t had a chance to listen to the ‘cast yet, just saw the text syndicated on Slate.

  7. Minor correction: While the beige phone in the photo may share design elements with 1970s phones, its AT&T logo dates that specific one to the post-Bell breakup design circa 1983. #phonephreak

    1. Shawn

      Also, I think we should collectively call it a brädgård from now on. #brädgård

  8. Ann

    So, this was the Octothorpe origin tale I heard growing up:

    “In cartography, [the octothorp] is a traditional symbol for village: eight fields around a central square. That is the source of its name. Octothorp means eight fields.” (From octo- (“eight”) and thorpe (“field, hamlet or small village”).)

    Sound familiar to anyone else?

  9. Mary

    Grammar nitpicking here but “comprise” was used incorrectly twice in the show.

    From AP’s Stylebook: “Comprise means to contain, to include all or embrace. It is best used only in the active voice, followed by a direct object: The United States comprises 50 states. The jury comprises five men and seven women. The zoo comprises many animals.”

  10. DBowie

    For the first time in the years I’ve listened to 99pi, I see other outlets (Guardian.co.uk, Slashdot for example) carrying articles about a topic (#) at the same time 99pi is covering the topic. In this age of instant content spread, I wonder if the 99pi episode is the chicken or the egg – no, originator or copier? Given Roman’s track record, I’d say originator. BTW 99pi does by far the best job of it.

  11. Chris vdL

    I’ll have to agree with Jon, but I have the book on my desk right here:
    The Elements of Typographic Style version 3.2 by Robert Bringhurst (p. 314)

    “octothorp Otherwise known as the numeral sign. It has also been used as a symbol for the pound avoirdupois, but this usage is now archaic. In cartography, it is a traditional symbol for village: eight fields around a central square. That is the source of its name. Octothorp means eight fields. [U+O023]”

  12. larnell

    Very interesting information about the origins of hashtags, its still evolving so its limitations are endless.

  13. It’s two sets of parallel lines, 4 lines, with one enclosed area or maybe 9 total areas. Why not quad[xxx]? What moron came up with octo?

  14. Great episode. Thank you! Two things: first, although you gave it a very brief shoutout at the end, the # sign has been used as a musical notation for approximately nine centuries (by hundreds of millions of people by now) to indicate raising the note by a half step, long before phones, typewriters, and even printing presses. It should have received a bit more coverage by you in my opinion. And secondly, Roman, it’s “asterisk”not “asterik”! Thanks for listening and please keep up the great work.

  15. Steve Davis

    One more usage: in computer science, # is used to indicate a hexadecimal number. Not sure of the origin of that usage.

  16. Cindy

    When my daughter was little (maybe age 4?) she read the buttons on the phone out loud: 1, 2, 3, 4, 5, 6, 7, 8, 9, snowflake, zero, waffle. My husband and I both loved the snowflake and the waffle. Twitter would be just a little more fun with waffles.

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