That includes gesture analysis, which looks at "co-speech gestures". Not posture or gaze, but winking, or sticking out your tongue, or how arms and hands move alongside speech.

Just to be clear, this isn't about sign languages. Those are systematic and rule-governed with elaborate syntax and vocabulary.

Signed languages are language, but gestures are "paralinguistic"; they accompany language.

Gesture analysts make their job easier by talking about different categories of gestures, which explain how they relate to meaning.

And those are:

Number one: Iconic. These gestures represent a literal object, like a flat surface, or a car weaving through traffic.

Number two: Metaphoric. Gestures that symbolize an abstract concept, like "before" and "after", or "working together".

I do that a lot, and on this greenscreen those metaphoric gestures become a bit more literal with the help of graphics.

Apologies to my animator.

Three: Deictic. That's pointing to things, positioning yourself to people, or places or things like pointing behind the camera or "over there".

Number four: Pragmatic. Like offering the floor to someone, or "don't bother me right now".

And finally, Beat. The rhythm of gestures alongside the natural stress patterns of speech.

All these categories — I'm, I'm really self-conscious about every move I'm making now.

These categories can coexist as well. Often gestures that are performed "on beat" also fit into another category.

There's one more type of gesture that serves a slightly different purpose: emblems.

Emblems are named gestures that don't have to occur alongside speech to have meaning, like "thumbs up".

It has a meaning outside of the context of speech. In a lot of the world, you can flash someone the thumbs up,

and they'll almost certainly understand that you're signalling approval, or that everything's okay.

But if you swap the fingers, it doesn't have the same meaning.

And even If I stick with the thumb, if I change angle and arm position, I'm trying to hitch-hike.

The form of the gesture is tied to the established meaning. It Is an emblem.

Which means it's not universal. The meaning is learned, and context can change it.

That thumbs up? In some countries, it used to be rude, but because of globalization, that's no longer the common reading there.

Although there will be people who remember its rude history, and could still interpret it that way.

Emblems can change definition over time, they can be created, they can be forgotten.

I would demonstrate that by dabbing, but I don't want a GIF of that to haunt me for the rest of my life.

So why do we do it? What does gesturing actually accomplish?

Well, first: redundancy for decoding and encoding errors.

Languages have agreement all over the place. There's redundancy baked into everything.

Spoken language is ephemeral. Once something is said, it's gone.

Those sound waves have moved on and they are not coming back.

Gesture is another form of redundancy. It doesn't matter if a loud [engine noise] drove by at just the wrong time — you may have figured out a vague idea of what was being said.

Next, you can show emphasis and importance.

Or if you're explaining an abstract concept, using metaphoric gestures to visibly explain things can help make it clear — either to your conversation partner, or just in your own head.

And sometimes, it is so much easier and clearer just to point.

Gestures are important to communication, and so important that if our hands and arms are unavailable, we will use our head, our eyes, our other limbs to compensate.

Gestures can also show understanding of social norms.

If you're embarrassed to say something, you can make that clear by covering your face or your eyes,

or by doing the move that looks like "There are no paper towels or hand dryers in this bathroom so I guess I'll just shake it off".

Or if you want to distance yourself from what you're saying you can use scare quotes, or you can put a boundary around yourself.

Gestures also seem to help us get the words out in the first place.

That's why people gesture even when they're on the phone, and why people who have been blind since birth gesture.

Gesture is intrinsic to language.

It helps us communicate more effectively and more elaborately, and to pass on information and feelings that are difficult to put into words.

Gestures are basically emoji for the real world.

One of my co-authors, Gretchen McCulloch, has a book called Because Internet, all about internet language.

You can find out more at the links in the description.