Hashtags are used for everything from connecting people with like-minded political views to grouping pictures of Pinterest fails.

But, after posting a slideshow of your dog's birthday party with the caption #blessed, have you ever wondered, where does that symbol come from?

[upbeat music] Whether it's knowing what's trending on Twitter or trying to remember impossibly long wedding hashtags, we can all admit that our favorite little symbol serves an important function-- grouping things together online.

But let's play a little game with our #bestie the hashtag.

Because when you see it here, it's a hashtag.

But what about here?

And what if we switched that?

Or how about if you see it and you happen to be a programmer or a chess player, or a coalminer, or a doctor?

But before you get there, you have to #askyourself-- "Where did that little sign come from, "and what are all of its meanings?

"And how did its current and most popular iteration, the infamous hashtag, get its start?"

Plus, how long are we going to play out this #weaksauce #joke?

We're done.

So, it seems like the first iteration of the hashtag goes all the way back to ancient Rome.

Romans used the abbreviation "lb," short of "Libra," to mark the measurement for "pound by weight," or libra pondo, which coincidentally explains why Libras are represented in astrology by scales.

Over time, scribes and writers started drawing a line through the top of the "lb" to note that it was a contraction.

And because not only doctors have bad handwriting, over time, this contraction started to look more and more like the pound sign.

In the late 17th century, Isaac Newton, of the infamous apple mythology started using the "lb" sign a lot, so much so that it was added to the early printing press.

The dates of the exact shift from the pound contraction to the pound sign are fuzzy, but most agree it was around the 19th century.

And what's interesting is that the hash sign has always had a unique relationship to technology.

In the mid-20th century, developers at Bell Labs started to transition the old rotary phones to a new style of keyboard where people could just push the buttons.

After fiddling around with different designs, they settled on a 3-by-4 square, but they were worried about the poor, little lonely 0 hanging out on the bottom row, so they decided to place our good buddy, the asterisk, on the left side and a diamond on the right, but the diamond didn't last long.

In the 1960s, Bell Labs started trying to get phones to communicate with computers, and the diamond wasn't really a part of programming language, because it wasn't on the QWERTY keyboard.

So they swapped out the diamond for another symbol on the keyboard, the good old pound sign.

Except, for some weird reason, they called it an "octothorpe."

Those of you old enough to remember when phones had buttons and not just touchscreens know that the pound sign was a pretty important key when dialing Moviefone or any other kind of automated phone system, and in my case, it was the last button you pushed to find out if it was a snow day.

So, how did this humble symbol become arguably the most important and trendy sign of the 21st century?

That's all thanks to a guy named Chris Messina.

In the ancient history of August 23rd, 2007, Messina pitched an idea on Twitter-- "How do you feel about using # (pound) for groups?

As in #barcamp?"

Messina, who was a developer at Google, thought that the hashtag had staying power, since it would allow Twitter to create hyperlinks between groups.

He said, "Twitter didn't support groups, "so I figured the next best thing to do was to use the text of a tweet to indicate topicality."

Messina also thought it sounded like a cool idea because there was some precedent for using the pound sign this way.

But Twitter shot him down because they thought the idea was "for nerds."

But we'll just have to call this #RevengeoftheNerds because the hashtag exploded, and all of us nerds are still using it today.

Okay, so we figured out the hashtag #historyofthehashtag.

I promise I won't do that again.

But why does it matter?

Well, if we take the origin of the hashtag one step further, it actually becomes a very interesting example of semiotics.

And trust me, just like the early hashtag, this is definitely for nerds, but still actually pretty cool.

In its most basic form, semiotics is the study of how language makes meaning.

And according to early semiotician, Ferdinand de Saussure, there are two key components-- the signified: the concept or object being represented or referred to.

This can be abstract or concrete, like anger or blub or, well, concrete.

The second key part is the signifier.

This is the word, symbol, utterance, etcetera, that's used to refer to the signified.

Okay, to understand this, think of an object or concept in your head, whether it's a chair, an apple, or the vague feeling of listlessness that is ennui.

Now, think of the thing itself as separate from the word.

Because those words and images you're using to describe the signified-- chair, apple, or the more fun-to-say ennui-- are not the thing itself; language never is.

In fact, many would argue that the utterances are somewhat, if not entirely, arbitrary.

We use signifiers as modes of communication to express both simple and complex thought, but they're not inherently tied to the thing they describe.

So imagine a world in which your word for "chair" was not linked to what we consider a chair, but actually lined up to the feeling of dissatisfaction we call "ennui."

So the sentence, "I feel ennui while sitting in this chair" could just as easily be: "I feel chair while sitting in this ennui."

And why does that matter?

Well, let's go back to our friend the hashtag.

It represents an interesting case study in semiotics for many reasons.

First, it developed alongside the evolution of new technologies like standardized measurements, the printing press, QWERTY keyboards, and touchtone phones.

But when the 21st century brought us Twitter, the hashtag shifted again.

So what the hashtag, or pound sign, or octothorpe signified was always changing.

If you went to someone in the 1960s and told them that the pound sign on their telephone would one day be useful for people sharing memes on smartphones, they would have had no idea what you were talking about, because Richard Dawkins wouldn't even coin the word "meme" until 1976, and the only thing a phone could do was let you talk to someone else.

But that same person who wouldn't have understood that concept in the 1960s is now your cool aunt hashtagging your baby pictures online.

What's weird is that we think of words and symbols as stable, because that's how we use them to communicate every day.

But both words and the people who articulate them express a certain amount of evolution and instability as symbols are used over time.

That evolution can be slow, like the "lb" sign, which developed over centuries, or rapid, like the hashtag, which took only a handful of years.

That's why etymology traces both the changes in words, like spelling and appearance, alongside the changes in human usage over time.

And the hashtag is a pretty great example of this.

Its shape and meaning had to be stable enough for people to use it in a given era, but it was also capacious enough to encapsulate new concepts as they emerged, even if those concepts rendered older meanings of a word out-of-date.

So, to paraphrase Shrek, words and symbols are like onions.

They have layers.

So, how does this all add up?

We started with a sign for measuring weight in ancient Rome, and evolved into a ubiquitous little swear that dominates our social media.

But the humble hashtag is also an example of how meaning exceeds the bounds of the signifier itself because even though both the signifier and the signified of the hashtag have changed through time and usage, there's a common feature in the pound sign, and that's grouping together both objects and concepts.

So whether it's adding up numbers, measuring weight, marking the end of a code, distinguishing qualities of sound, or even linking together people with similar interests online, this symbol is pretty great for holding things together.

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