Hi, I'm Cristos Goodrow.

I'm Johanna Yulich-Wright.

We're from the YouTube search and discovery team.

And this is the Wired Autocomplete Interview.

[funky music]

What we do is we help our viewers find the videos

that they want to watch.

[funky music]

How YouTube uses machine learning.

YouTube uses machine learning in two basic ways.

The first way is to keep the site safe.

So we use machine learning to comb through the huge database

of videos and find anything that violates

our community guidelines.

And if something doesn't pass our community guidelines

based on our machine learning,

then we'll send it out to human evalsuators

and they will make a judgment about whether or not

that video should come down.

And the other way that we use machine learning

is to keep the site fun.

There we use it to build out our recommendation engine.

So the home page, the watch next, search engine.

Also, we have our own YouTube auto-complete,

just kind of like this

and that is built by machine learning.

So the latest and greatest form of machine learning

is often called deep neural networks.

It's basically you're creating a network that's a little bit

like what you might imagine your brain.

And then you're putting a bunch of information

in the network.

And then these neurons all pass that information through

to try to get an answer.

And the way you train this is by basically doing that,

getting an answer,

showing this network what the right answer was.

And then the network tries to adjust itself to get closer

to the right answer the next time.

The first places that we started using deep neural networks

was in recommendations.

But now it's permeated many other parts of the system.

How to compress, or what's the best way to stream a video,

the quality of the network in that locations,

and things like that.

How YouTube algorithm works.

How many lines of code is the algorithm?

Oh my gosh.

I would say it's in the hundreds of thousands at least.

How YouTube search works.

We actually call this our search and discovery system.

This is the system whereby we show people videos,

recommend videos to them.

Our goal is to make sure that everybody has a video

that they want to watch.

And we do this by using over 80 billion signals.

Things like videos that you've watched before,

clicked on, liked, disliked.

Actually one of the biggest pieces of the algorithm

is people who watch things like you have also watched.

So just this notion of the wisdom of the crowds

is a really big piece of the algorithm.

YouTube search tries to find the video that you're looking

for based on the query that you've entered.

It does this by using the query,

the terms in the query, and matching them to the information

we have about the video.

In particular the title, the description,

and even some information we might have

from the video content itself.

Now for some kinds of queries,

for instance entertainment queries,

we're really trying to find the video that you're most

satisfied with and that's most relevant to the query.

But for certain topics like health and politics,

we want to make sure that the videos that are at the top

come from credible trustworthy sources.

For news and for health and for sensitive areas,

we always try and raise up authoritative sources.

But then in other areas like entertainment areas,

we rely on things like clicks

and other things to determine the relevance

and how closely related the results are to the query

the person has entered.

How YouTube ranks videos.

Well, we use over 80 billion signals.

In the case of search results we are really focused on

matching the video to the query that the user has entered,

but in our homepage and our watch next,

we use signals like what videos you've watched before,

liked, disliked, clicked on,

how you've responded to surveys about those videos.

How YouTube recommends videos.

We use our website, our app,

and we put videos that we recommend on the homepage

and also right after a video you've watched.

So we use those surfaces as a place

to recommend videos to people.

We try to make sure that the videos that are recommended

are the ones that you'll find the most value from.

Particular, we send people surveys after they've watched

videos asking them how did you enjoy this video?

And would you rate it from one to five stars?

And we try to make sure that the recommendations we make

in the future are those that will only get four

and five stars out of five.

You might ask, why does YouTube even recommend videos?

I think the best way to think of this is that YouTube

is like a modern library.

A library might have thousands of books

and have librarians helping you find what to read.

Whereas at YouTube we have billions of videos

and without a recommendation system,

how would you know what video to watch when you get there?

So that's why having a recommendation system

is so important.

How YouTube views translate to money.

So for YouTube creators who've joined our partner program

we share revenue from the ads

that are played on the videos

when people watch from your channel.

When you watch a video, a watch turns into a view.

Does YouTube count your own views?

Yes, YouTube does count your views.

If you watch your own video, YouTube will count those views.

Now of course, if you just try to refresh the browser

to get more views then YouTube won't count those.

So if you watch your video a few times,

YouTube will definitely count them.

Some might wonder is there a way to like hack the view

so that I could just get lots

and lots of views on my own video.

We just have lots of mechanisms at YouTube

to prevent spam and things like this.

So yeah, you can watch your video once or twice,

but you can't like run a video watching farm

of your own video.

That's not gonna be allowed.

You're not gonna be able to raise the views that way.

Does YouTube count views without account?

Yes.

If you're logged out and you watch videos,

then those views will get counted.

Does YouTube count loops as views?

Yes, I think we do count loops as views.

Does YouTube count repeat views?

Yes, YouTube counts repeat views.

There's not a particular cutoff

for how long you have to watch it.

I think the system that does the counting of the views

makes a decision about that

based on the setting that you're in.

So it may be different if, for instance,

your watching a playlist of videos,

versus if you're maybe finding a video on some other website

and clicking on it.

What YouTube, what YouTube first video?

Oh, this was me at the zoo by our founders,

Chad, Steve, and Jawed.

Starring Jawed standing in front of an elephant

at the zoo.

What's YouTube's most liked video?

Well, the most liked video is Despacito.

Despacito.

Despacito is the most liked video

because Despacito is awesome.

It's also in a very popular language.

So people listen to it in English,

but it's also sung in Spanish

so it's got the opportunity for a huge global audience.

That's right.

What's YouTube's most viewed video?

Okay, this is my turn to sing.

[singing rhythm]

Oh no, is that Baby Shark?

Yeah, Baby shark is the most viewed video.

I think something like Baby Shark is something

sometimes people love to hate, right?

You love to hate Baby Shark.

So that's why I think it's the most viewed,

but potentially not the most liked video.

And the first video to get a billion views

was oppa Gangnam Style.

Yeah, Gangnam Style was actually the reigning

most viewed for quite some time.

And that's interesting because again,

another video that wasn't in English,

but appealed worldwide.

Likes are many fewer than views.

They tend to be a slightly stronger indication

of appreciation or value on the part of the viewer.

But we found that people will like videos

for a variety of reasons,

not just because they really enjoyed it.

What YouTube record did BTS break?

I believe that BTS broke that top views in 24 hours,

108 million views in 24 hours.

BTS Butter was the video.

Current record holder, BTS Butter.

So would you say that BTS was doing us a favor

by having such an awesomely popular video?

BTS should absolutely make more record-breaking videos.

That would be fabulous for, for everybody really.

What YouTube knows about me?

I don't know what YouTube knows about you Cristos.

That is an interesting question.

YouTube typically knows the videos that you've watched,

the things that you've liked, that you've disliked.

You have a profile, you can enter things like your age,

your name, you can put in a profile picture,

you can look and see your watch history

and so you'll know what videos you've watched and liked.

And it knows what I subscribe to.

It knows what I've uploaded, keeps track of that for me too.

You can change your settings

to have it store the data forever.

And that's what I do because I really like it to remember

which things I like and which things I didn't like

and improve my recommendations.

But if I ever decide that I don't want it to have that data

anymore it's very easy to delete it.

Why YouTube was created.

YouTube was created to give everyone a voice

and show them the world.

YouTube was created as a way for people to share videos

at a time when it was becoming possible to create videos

and upload them and share them via the internet.

Why YouTube is called YouTube.

Because you put the you in YouTube,

the user generated content.

And because tube is what we used to call televisions.

So you put those together and you get YouTube.

Why YouTube ads are annoying.

Are they annoying?

I'm sorry, we're sorry that they're annoying.

We endeavor to find ads that are not annoying.

I myself have found some really great ads,

but if you don't like an ad

then on the mobiles app,

you can actually dislike it.

And that will encourage the system to not show you

that kind of ad again.

Why YouTube recommending old videos.

We want to make sure that we can recommend the new videos

that are uploaded as quickly as possible,

but there are also old videos that are fabulous.

And we want to make sure that people who enjoy those

will get those recommended as well.

Really, sometimes these old videos can really be a gem.

There really are some esoteric, cool videos on YouTube.

And the system doesn't really expire videos

after a certain amount of time,

if it's still available,

they system's trying to find an audience for it.

Why are YouTube recommend same videos.

Ugh, we'd rather not the system recommend the same videos

all the time.

Sometimes this is great because you're into a particular

topic or you want to see something again,

often music videos.

People like to hear music videos again and again.

But in many cases, this is not great.

One of the issues I've noticed though

is that people might use different accounts or devices.

Sometimes they're logged in, sometimes they're logged out.

If the system can't keep track of the videos that you've

watched across those accounts or devices,

then it really has no way to prevent

recommending the same thing to you.

Sometimes videos aren't technically the same,

but they might seem the same.

Just think about like two videos that are re-uploaded

and are kind of similar or it's just the same creator.

And they make things that are kind of alike.

And so you're like, oh man,

I've seen so much of this similar creator

that you feel like it's the same.

So sometimes we look at complaints from users saying that

they've been recommended the same video

and it turns out they actually haven't,

but it still feels the same.

So this is actually just a really,

it's really a tricky area for us.

Does YouTube channel locations matter?

I think the biggest thing to think about here

more than like where you post is is something like language,

language probably matters a lot

since YouTube is a global site.

People from all around the world watch YouTube.

So if you're gonna have a video in Spanish,

you might have a much wider audience than say

if you were posting a video in French.

Does YouTube description matter?

It does matter.

We see a lot of our viewers clicking on it

to learn more about the video.

So making a good description will matter.

People will read it.

And we use that description in search,

along with the title and other information about the video

to match the query.

Does YouTube favor longer videos?

This I believe within the creator community

is a hotly debated topic

and our systems don't inherently like one video length

more than another,

but different people do favor different length videos.

Say Cristos likes long videos.

What we will endeavor to do

is to recommend him longer videos.

And if I like shorter videos,

we will recommend me shorter videos.

And so this is really a personal taste.

And if YouTube favored longer videos,

then how could we explain the popularity

of music videos on YouTube,

which aren't really that long?

Does YouTube favor new channels?

we try to make sure that the site is fresh and relevant.

And so that may be from new channels, but also old channels,

uploading new videos.

New, old, all should have a chance to succeed.

And our system really does try to find an audience

for brand new channels.

It's challenging, but we have special parts of the system

that are designed to try to help new channels

find an audience.

If you're a creator, you might be thinking, oh,

should I make a new channel?

Would it favor that?

But it's actually hard for YouTube to favor new channels

because once a channel has existed for awhile,

it develops a lot of history.

It's developed an audience.

YouTube will know which people

will want to watch those videos.

If you're a new channel, none of those signals,

none of that information exists.

So we want all new channels to succeed,

but it's actually hard for us to favor new channels,

even if we wanted to.

Who trending on YouTube?

I don't know.

Who's trending on YouTube.

Might we have to check and find out.

Mr. Beast? Mr. Beast maybe.

Squid, Squid Game I think.

Trending tries to find the videos that are catching on.

And that usually means that they're getting a lot of views

relative to what we might otherwise expect for that creator

in a very short period of time.

So they're, they're kind of like spiking.

Where to upload YouTube shorts?

You can upload YouTube shorts from your mobiles phones.

If you have the YouTube app on a mobiles phones,

then you just push the plus button,

the create button, select create short,

and you can add effects and add music

and just have a fun time creating a short and uploading it.

Can YouTube auto translate?

It sure can.

YouTube can absolutely auto translate,

making that system better and better all the time.

And you can turn on the translated subtitles

right in the YouTube player.

This is actually one of our most powerful features,

especially for people who speak languages

that there has not been as much content written in.

So around the world, like in India,

there's many languages spoken,

but maybe there's not as much content written.

You can get content auto translated from English

or other languages, Hindi, into your language.

It's really a big deal more globally

maybe than in the United States.

Can YouTube find you fine you?

Fine you, I don't think so, no.

YouTube cannot fine you.

YouTube Wired autocomplete.

Wait, that's us right?

What we're doing right now?

Are we supposed to answer that?

Interestingly recursive.

I think the easiest way for Wired to get more views

of this video is to make sure that we look very cool

and are very funny so people want to watch it.