You've probably seen them here and there… at the check-out display of your local grocery store, filling an entire section of a book or craft store, or maybe even in action at your favorite coffee shop.

Adult coloring books, initially considered a curious fad when they started appearing a few years ago, have suddenly turned into a popular pasttime for creatives of all ages. In the last year, coloring book sales in the U.S. exploded from 1 million to 12 million. Currently, four of the 20 top-selling books on Amazon are adult coloring books. And colored pencil sales have skyrocketed over the past year, leading to rumors of shortages around the world.

At first glance, coloring might seem like a silly little hobby, a pointless waste of time. Don't most adults have better things to do than apply color to pictures of animals and mandalas?

Sure they do. And in many cases, that's exactly the problem.

Fans of coloring – often referred to as “colorists" – say that coloring gives them a therapeutic sense of calm, a way to unplug that is simple, nostalgic and socially engaging.

The Coloring Project/Illlustration by Kristen Lawrence

'A Mental Massage'

Allen Wills, a 28-year-old photographer who works out of Impact Hub, a coworking space in Seattle, says he was introduced to coloring when another member hosted a “creativity break" one afternoon a couple months ago.

“At that particular moment, I was really stressed and probably needed to take an hour or so to unwind," says Wills. After just a few minutes of coloring, he understood the appeal. By the end of the session, “I felt more mentally ready to take on my workload," he says. “It was like a mental massage."

Wills says he thinks coloring is taking off in the U.S. because the cultural norm is to burn the candle at both ends. “People don't take the time to recreate or relax in general," he says. “But everyone loves coloring. Show me a kid who ever hated coloring."

In fact, Wills says coloring has actually strengthened his relationship with his 8-year-old niece, whom he hangs out with regularly. “Previously, I would supervise while she colored, but I was never actively engaged. So it has been fun exploring that with her." Now they pick out new coloring books together.

Katy Lipscomb, a 22-year-old art student at the University of Georgia who illustrated Howl, a wolf-themed coloring book for adults, thinks the new resurgence in coloring is absolutely a way to reconnect with our younger years. “Coloring is so ingrained into childhood and I think everyone secretly wishes they could revert back to that childlike stage at some point," she says. “This makes it OK; even having 'adult coloring' in the title gives permission."

As an artist, Lipscomb admits she didn't entirely understand the appeal of coloring within the lines until she decided to color some of her own designs for the purposes of promoting her book.

“It was so much fun; that's when I sort of got it," she says. “There's something so relaxing about having the page finished and not having to think about the design."

Blue Star Coloring's new Master Collection of coloring books. 

Unplugging for Productivity

Andrea Koehler, who hosted the creativity break that Wills attended at Impact Hub, is something of a coloring advocate. The 42-year-old picked up her first coloring book about a year ago, curious about the new trend. She enjoyed it and began researching some of coloring's therapeutic benefits, including the possibility that it can help quiet anxiety and increase focus.

As an ontological coach (she helps people reach personal or professional goals by working through limiting beliefs), Koehler began recommending coloring to a few of her clients. Today, through her business, The Coloring Project, she sells coloring pages that feature inspiring messages (like “Gratitude" and “You are the expert on you") and incorporates coloring activities into team building workshops and other facilitated events for corporate clients.

In addition to providing relaxation, Koehler says coloring can help boost creative thinking and problem solving. “Brains are really powerful things, but they get in our way a lot," says Koehler. “Big ideas and big shifts in understanding usually happen when you're not doing the thing you're working on." In her work with corporate clients, she finds that when a group of people are coloring, their discussions are more open-minded.

Koehler and other coloring fans also point to the concept of “flow," the state of being fully immersed in an activity, which can be hard to accomplish in our digital age.

“We're driven by our calendars and constant pop-ups of information," says Koehler. “But when you're coloring, you're not getting that constant interruption."

Camden Hendricks is co-founder and CEO of Blue Star Coloring, a coloring book publisher that only launched about a year ago and has already sold around a million copies of about 30 titles. He agrees that part of coloring's popularity comes from its non-digital nature. “Some people say it's just nostalgia for childhood," he says. “But people are on computers and phones all day. There's no tactile connection; people don't even write handwritten notes any more."

The Coloring Project/Illustration by Justine Fisher

Face to Face – or Phone to Phone

If people are craving tactile connection, they're also craving human connection. And colorists today are finding that their hobby can be a great way to connect with others. There are currently 112 Meetup groups dedicated to coloring, and many of them are quite large, boasting hundreds of members. Koehler's Meetup in Seattle has nearly 500 members and meets in different locations up to eight times a month.

“Ten to twenty people who have never met before are talking like they're old friends at the end of an hour," she says. Koehler has found that while other networking groups are often focused on a certain industry or field, coloring get-togethers are more diverse in age and background. “It crumbles the borders between what people do for a living."

Shannon Sayama, a 24-year-old blogger in Orange County, Calif., started the Yorba Linda Adult Coloring Group Meetup (an affiliate of the Salt Lake City group) with her mom in February. The group already has more than 100 members, and up to 30 people attend each event.

“It's a great way to connect with new people in various age groups, and it's a way to show your creativity whether you knew you had it before or not," says Sayama, who also cites coloring as a tool to alleviate inflammation in her hands due to rheumatoid arthritis. While she enjoys meeting her fellow colorists face-to-face, Sayama also shares her completed coloring projects via social media.

The Coloring Project/Andrea Koehler

'Everyone's an Artist'

Peter Licalzi, the other co-founder of Blue Star Coloring, and its chief marketing officer, says not only is coloring perfectly suited to being shared on social media; it effectively levels the artistic playing field like some social media apps, too. “I compare it all the time to Instagram, which gave everybody a tool to be a photographer," he says. “With adult coloring, everyone's an artist now."

But it's not only the colorists who are sharing their work online; many of the coloring book creators are, too. Lipscomb, for example, says posting to social media has become both a daily ritual and a form of market research. “I try to keep up with popular trends and I want my work to be consumed by the masses" she says. “So I'm constantly taking in that feedback and making alterations depending on how the work is perceived."

So, with coloring, as with so many things these days, the line between the “real world" and the digital world is often blurred, as Instagram hashtags like #adultcoloring and #colouringbook prove at a glance – tens of thousands of hand-colored images displayed online.

But maybe what the adult coloring craze comes down to is much simpler than all of this. Could it be that coloring is just… fun?

“Most of us are so busy doing things that 'need' to be done," says Koehler, “we forget that fun is a need, too."