How Exactly Does Netflix Recommend Movies To You?

If you have ever wondered how Netflix's recommendation system works, here is a quick overview.
Christopher McFadden

With thousands of TV shows and movies on Netflix, how do you chose what to watch? The simple answer is that Netflix offers you a hand-picked selection right to your screen.

But this belies a complex interplay of user data, machine learning, and clever algorithms that drive the process behind the scenes. And, they are certainly not starved of user data.

Netflix, to date, has just over 100 million subscribers on its platform. But with each subscription having multiple profiles, the real number is double that. 

That's a lot of data, and with over 80% of TV shows being watched on the platform, it has its work cut out, to keep people engaged. But it doesn't have to do all the hard work.

Netflix effectively outsources some of the processes to you. Information on how you use the platform, how you rate content, and what you search for are all harvested and analysed by Netflix to better improve your user experience.


In the following article, we'll take a look "under the hood" regarding Netflix's recommendation system and provide some answers to other common questions.

How does Netflix choose the movies I see?

Netflix uses a combination of machine learning, data from its users, and algorithms to rank order its content and decide what to show you on your account. If you want to know how, Netflix offers a helpful overview of their system on their website.

In an interview with Wired, Todd Yellin (Netflix's Vice President of Production Innovation) explained that you can think of their system as something of a three-legged stool.

"The three legs of this stool would be Netflix members; taggers who understand everything about the content; and our machine learning algorithms that take all of the data and put things together," he said.

netflix recommendations algorithm
Source: Matthew Keys/Flickr

"Whenever you access the Netflix service, our recommendations system strives to help you find a show or movie to enjoy with minimal effort. We estimate the likelihood that you will watch a particular title in our catalog..." - Netflix

It does this by using a variety of factors. These include:

- how you interact with their service (like your viewing history, search queries, and personal ratings of content);

- data collected from other members on the site with similar interests to your own; and,

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- linking all that to information about the titles, such as their genre, categories, actors, release year, etc. over their content.

The whole personalized recommendations process begins when you first open your account or add a new profile to it. At this point, you are asked to choose a few titles that you like. 

netflix recommendations machine
Source: Brian Cantoni/Flickr

Netflix uses these choices to "jump start" the recommendation process. If you avoid this step, the algorithm takes a little longer to "learn" about your personal preferences. 

"We take all of these tags and the user behavior data and then we use very sophisticated machine learning algorithms that figure out what’s most important - what should we weigh," Yellin says.

Netflix also takes note of other watchers' habits, like the time of day you tend to watch, which devices you use, and how long you watch particular content. According to their website, it does not take demographics (age and gender, etc) into account.

"How much should it matter if a consumer watched something yesterday? Should that count twice as much or ten times as much compare to what they watched a whole year ago? How about a month ago? How about if they watched ten minutes of content and abandoned it or they binged through it in two nights? How do we weight all that? That’s where machine learning comes in. What those three things create for us is ‘taste communities’ around the world. It’s about people who watch the same kind of things that you watch." Yellin added.

All of this information is then fed through their own in-house algorithms to provide, to the best of their ability, a highly personalized recommendation list to you.

How do I recommend a movie to Netflix?

If you are fed up with not finding that movie you fancy watching on Netflix, you can actually recommend it to them to consider adding it later down the line. This is something that is not widely known, but it does exist.

On Netflix's request page, you can request up to three movies or TV shows that they don't have and that you like. You could, for example, request that they bring your favourite tv show or movie series. 

But, just because you have recommended something to be added that doesn't necessarily mean they will, or can. Once you submit a request, Netflix notes that, while they do appreciate the feedback, there are limits to what they can do.

According to Mashable, Netflix explains why:

"While we love hearing your suggestions, sometimes we just aren't able to license a particular movie or TV show. Reasons we might not be able to secure a license include:

- The content rights are currently exclusive to another company.

- Example: Game of Thrones is an HBO Original Series.

- The streaming rights are not available to purchase from the content provider.

- Other factors, including popularity, cost, or seasonal or localized availability."

How do you rate Netflix movies?

Rating movies, or TV shows for that matter, on Netflix, is actually pretty straight forward. It's also a pretty useful thing for you to do so Netflix can better tailor their recommendations to your actual tastes and likes. 

The process couldn't really be any simpler:

- Launch the Netflix app from the Home screen of your smart devices, gaming console or computer;

- Search for or tap on the movie or show you've watched that you'd like to leave a rating for;

- Tap on the red stars to the right of the movie or show banner. They should then turn yellow;

- Tap on the number of stars you'd like to give the movie or show to add your rating.

That's it, easy as pie.

How do I clear my Netflix recommendations?

If you have ever wondered if you can clear your recommendations on Netflix, it is actually possible. The process can be thought of as selectively deleting sites from your browsing history on a search engine like Google.

By doing this, you are effectively resetting some parts of Netflix's algorithms for your profile and may see a lot of content you may not be interested in watching. For this reason, doing so will likely mean that you will spend a lot more time searching for titles. 

But it could be useful in the event of something like a breakup where multiple users have accessed the same profile, for example. 

Much like the rating process, clearing your viewing history and other user data is fairly straight forward too. But it is a little more labor intensive.

To this follow these steps:

- Open Netflix on your smart device, games console or computer;

- Hover over your profile picture in the upper-right corner of the screen;

- Click on "Account";

- Click "Viewing Activity" under "My Profile";

- Click the 'X' next to a title to remove it from your viewing history;

- Click "Remove Series?" if you want to completely remove an entire series, obviously.

Any title removal requests made will be deleted from your watch history within 24 hours or so. Sadly, it is not possible to delete your entire watch history at the same time.

You could also consider closing your account and opening a new one if you really want to start from scratch.

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