In 2018, more than 25 years after the term Millennial was first applied to a generation, the Pew Research Center finally nailed down a finite age range for that demographic: anyone born between 1981 and 1996. (Those who missed the closing cut-off were just considered “Post-Millennials,” though they got their own official moniker, Generation Z, when Pew Research updated its generational guidelines the following year.)

By that point, Millennials were already in their twenties and thirties and well into establishing their own cultural trends. Chief among them was Millennial Pink, a somewhat ambiguous color that took the design world by storm—and still, impressively, has yet to relinquish its hold. Here are all the details about what it is and why we love it.

What Is Millennial Pink?

Unlike Water Ballet or Cinnamon Swirl, Millennial Pink isn’t the name of a specific Pantone color. Instead, it’s an unofficial term for an equally unofficial family of colors that includes everything from pink-ish beige to muted salmon. What unites the hues is their softness; if it looks like something your old Barbie dolls wore, it’s probably too bright to be considered Millennial Pink. Though the shades started creeping up in fashion and advertising nearly a decade ago, it took until 2016 for Millennials to realize that, seemingly suddenly, their entire lives—clothes, product packaging, advertising, decor, etc.—were coated in a lovely, if a bit dull, light pink.

“A cohort raised to distrust pink has turned contrarian and embraced a muddied, faded version of the color,” Véronique Hyland wrote for The Cut in August 2016. “This summer, we’re conspicuously reading Sweetbitter, drinking a matching glass of frosé, and Instagramming it all with our rose-gold iPhones.” In that same article, Hyland suggested that we call it Millennial Pink. The nickname stuck.

Why Do Millennials Love Millennial Pink?

Apple snail eggs, which you can feed to your pet fire ants.Sataporn Kumsuka/iStock via Getty Images

Millennial Pink itself has proven just as hard to shake, which has prompted people to wonder whether there’s some scientific explanation behind it. There’s not much evidence to support the theory that it’s an evolutionary gravitation. Sure, humans have positive associations with certain edible pink plants, but as Bustle points out, pink can also be a danger sign. The apple snail’s pink eggs, for example, are poisonous to every animal but fire ants. And eating a flower from an angel’s trumpet plant will, if it doesn’t kill you, at least send you into a state of hallucinatory delirium.

The closest anyone’s ever gotten to pinpointing a scientific reason for humans’ affinity for light pink was probably Alexander Schauss in the 1970s. Schauss painted prison cells a color of his own creation called “Baker-Miller Pink”—a bit brighter than Millennial Pink, but still more or less comparable—and observed its impact on the inmates. According to his and other experiments, the color helped reduce aggression; and additional tests suggested a link between Baker-Miller Pink and reduced strength and even blood pressure. Overall, Schauss’s work implied that the color may have some calming properties. That said, other researchers contested his conclusions after failing to find similar trends in their own experiments [PDF].

So we can’t exactly say that Millennial Pink is so popular because it invariably triggers physiological calmness. But the fact that Millennials in particular find it calming—even if it’s not necessarily lowering their blood pressure—suggests that something about the color endears it specifically to people born between 1981 and 1996.

There are a lot of theories about what that something might be, and the answer probably isn’t one-size-fits-all. For clothing designer Ryan Roche, it’s unadulterated nostalgia: Her 2013 clothing line was the same dusty pink as a My Little Pony she had as a kid. “I just remember thinking, ‘That looks delicious.’ Looking at it is like touching the softest cashmere,” she told The Cut.

For others, it could be more of a reaction to childhood than a tribute. The hot pink hues so common from the ’80s to the early aughts practically screamed “Girls only!” The quieter Millennial Pink reflects the much more gender-fluid, self-aware atmosphere that Millennials have fostered and embraced. It’s not just a quiet color when compared to the garish palettes of decades past. As The Cut’s Molly Fischer explains, it’s also a soothing break from the harsh light of a phone screen, delivering an endless stream of not always great news.

As for whether Millennial Pink will have the same appeal for Gen Z or even Generation Alpha, the jury’s still out. But considering the recent resurgence of early 2000s trends, hot pink may be mounting a comeback.