'Stranger Things' addict? Here’s how Netflix sucked you in

One of Netflix 's highest aspirations is to get you binging on shows like Eleven wolfs down her Eggo waffles.

Netflix, the world's biggest subscription video service by members, tends to jealously guard its data. But ahead of the season 2 premiere Friday of supernatural thriller "Stranger Things," the company lifted the curtain on some of the tricks it uses to entice its members into clicking play. From tags to "taste communities," Netflix tries to personalize its service, right down to the image you see splashed across your screen when you fire up the app.

"If you look at someone else's Netflix screen, not only will they have different titles featured," said Todd Yellin, Netflix's vice president of product, in a presentation to reporters last week. "Even the images around each of the titles is catered to each individual member."

It's a rare look inside the machinations of the video service, which is aiming for global video domination one original show or movie at a time. The stakes are high for Netflix, which said it will spend as much as $8 billion on programming next year.

That's why shows like "Stranger Things" are so critical. It's a worldwide hit, literally -- the company found one person who watched the first season in Antarctica. To help spread the word, Netflix starts by figuring out the nuances that define the show.

Netflix hires taggers around the world who watch every piece of content and tag it for things like tone -- tense, ominous, scary -- and storyline -- buddy story, missing person, family in crisis. (If you're wondering how you could land one of these paid gigs, Netflix says they're posted to its jobs website when they become available.)

More than one portal into the Upside Down

Netflix's algorithm applies 12 tags to "Stranger Things" to capture nuances of how different people relate to it. That means that while some of you see "Stranger Things" in a row for TV mysteries, others find it in sci-fi thrillers.

To figure out clusters of shows and movies that seem to appeal to the same people, Netflix has identified 2,000 "taste communities." "Stranger Things" is the most popular title in "a bunch" of those, Yellin said.

While "Stranger Things" may top many taste communities, it doesn't mean those lists are identical. One taste community with "Stranger Things" as No. 1 had horror items like "The Mist" and "Scream" in its top six, while another placed "Stranger Things" at the top of ahead of teen programming like "13 Reasons Why" and "Pretty Little Liars."

Getting personal

Movie recommendations aren't the only things Netflix personalizes. It tailors how your recommendations look, too, by specializing the image that accompanies them.

Netflix found that people who like documentaries were more likely to watch "Stranger Things" if it had a picture of Chief Hopper in his uniform. People who gravitate to action, horror and romance were more likely to click on the title with an image of Eleven staring intensely, while drama fans were most attracted to a picture of Eleven from far away.

Picking the images is "a mixture of art and science," Yellin said. The art comes from finding a diversity of strong images for the show. Then, through an image comparison method called A/B testing, "within a day, we home in on 'This kind of image is resonating with this kind of viewer,'" he said.

First-timers

The company also approaches promotion differently depending on whether you've watched a program or not.

The debut of the second season, Netflix has found, is a good time to target people who haven't watched the show at all. In the year since the first season of "Stranger Things" landed, Netflix has compiled data about people who it believes would like the show but haven't watched yet. "Someone who hasn't, we want them to start it at season one, episode one," he said.

Video promotion is "the next frontier" for Netflix, Yellin said. If you watch Netflix on a TV, you've probably noticed it automatically playing a trailer, the opening credits or the show itself after a few seconds. But the next stage of video promotion will likely personalize the clip that unspools, much like title images are tailored today, Yellin said.

Something that sets "Stranger Things" apart from the average show on Netflix is the screen you watch it on. Generally, about two-thirds of Netflix viewing is on televisions -- but for "Stranger Things," the proportion of big-screen viewing is higher.

As of this month, Netflix has more than 1,200 hours of 4K content and more than 200 hours of content using an imaging technique called high dynamic range (HDR), and it says those high-quality image formats are growing in popularity. Netflix expects viewing of "Stranger Things" season 2 to have four times as much 4K watching compared with the first season, Yellin said.

All the better to capture every nook and cranny of that Eggo waffle.

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