We live in a wonderfully colorful world. Let's celebrate that... by grabbing some pencils and pens, and scribbling between the lines.

For many years, coloring books have been viewed as merely things for kids. But no longer. People have finally embraced their inner child and accepted that coloring is awesome. It's just art without the hours working out proportions.

From now on, please excuse some colorful language. (Sorry.)

Johanna Basford

Arguably, the craze began in 2011 when Laurence King Publishing, British specialists in creative art books, approached Johanna Basford to create a children's coloring book. Basford had been illustrating labels on wine and perfume, and asked the company if they would instead publish a coloring book for adults – many of her clients, she argued, enjoyed peeling off the labels she'd created for that reason.

They agreed to take the chance, and Secret Garden: An Inky Treasure Hunt and Coloring Book has since sold nearly two million copies worldwide since its 2013 publication.

Johanna's own site doesn't just push her own books: it's a friendly, fresh layout and her gallery encourages fans to submit their own pictures, including details of which pencils or pens used.

Check out her blog too. It's not updated very often, but just occasionally you get a glimpse behind-the-scenes. Plus there's a Valentine's Day printable design for anyone who doesn't simply want to give a geeky gift or a pretty poem.

Want to try out some of Johanna's designs for free? The Guardian's got you covered with free coloring templates.

Zone Out: Coloring Life

Coloring Life

Why is coloring so popular right now? Partly because it's fun, yes, but also because it's excellent for relieving anxiety -- indeed, it's often billed as "anti-stress", while promoting mindfulness. Dr. Joel Pearson, a psychology lecturer, told Business Insider:

"When coloring you have a defined task which is challenging enough but not enough that it become problematic. It’s repetitive but you don’t become bored... [Coloring occupies] those parts of your brain that might normally be involved in anxiety."

Filling in a pattern, he argues, relieves stress better than simple random scrawling's on paper.

Coloring Life is perfect for anyone starting out, or looking for a basic design to fill in, in the hope of restoring a bit of Zen to your life.

After a hard day's work, coloring mythical beasts or symmetrical flowers while a relaxing piece of music plays in the background will stop you worrying about deadlines and arguments with management. It's even better if that music is completely free!

Delight in Detail: Pages for Adults

Coloring Pages Adults

If you're looking for intricacy, Coloring Pages for Adults has an extensive archive of images ready to print, all based around different themes. These range from typical Mandalas (Indian spiritual arrangements of squares and circles that have been largely adopted by coloring enthusiasts) to the far more unusual.

Here, you'll find landmarks from New York and Paris; African masks; artistic masterpieces (van Gogh's paintings naturally crop up a lot) and specific movements like Art Nouveau; and psychedelia.

You might be instantly grabbed by Egypt & Hieroglyphics or Landscapes, but it's worth perusing the Unclassifiable section too, and take on 100 buttons or the cover to Michael Jackson's Dangerous album!

The TV series and Movie Posters are interesting additions, offering pictures from The Walking Dead (still more relaxing than playing zombie games), and Game of Thrones (don't worry: it's spoiler-free!). There's even a mash-up of zombie hordes attacking Marvel Comics' Punisher. However, some images are clearly just grayscale-like pressings of actual photos, so they may be difficult to color.

One of Us: Color Me Club

Color Me Club

Of course, a big advantage of this craze is that you're part of a bigger community. It's cool to be coloring in. People are proudly admitting that they like to spent hours with a set of Sharpies; this includes writer, Matt Cain, who told The Guardian:

"If I switch off the phone, computer and TV and concentrate solely on choosing the right shade of blue, avoiding going over the lines and slowly filling up my page with colour, all my other concerns, I’ve discovered, fade to nothing. And not only that, but when I step back to admire my finished work, I sometimes find I’ve come up with a solution to a problem that’s been bothering me for days."

Thanks to social media, coloring isn't an isolating experience. Johanna's Gallery proves that peers want to share their work, and scouring Twitter feeds is a great way of checking out the competition and discovering new things (Querkels, for instance, or books related to TV shows like Outlander).

And if you check out this coloring club on Deviant Art, you'll get a seemingly-endless supply of users' templates!

You get a lot of material relating to comic books – but the geeks have inherited the Earth, so that might be just up your street. Otherwise, there's abstraction, realism, Manga, and landscapes, alongside colored examples of others' works. It's part inspiration, part free layouts. Some of the line art aren't that good, true, but submission guidelines mean the core of the club is superb art ready for you to scribble on.

Beware, this is one of the only places -- in this list at least -- where you'll find decidedly Adult (read: Mature) content. Perfect for the Fifty Shades of Grey generation.

Colors and Crafting: Easy Peasy and Fun

Easy Peasy and Fun

If you're a creative type who wants to add some color to life, Easy Peasy and Fun offers not only printable pages, but also general crafting – and a bit of bakery too!

Set up by Andreja Vucajnk, the blog is full of activities for you to do on your own, or even with your kids. These include recipes and papercraft (ideal additions to fans of these origami sites), and if you refine the posts to solely printables, you get images to color in that are generally a good mix of recognisable patterns – animals and plants – and abstractions to really help you relax. Indeed, coloring has affected those getting into papercrafts, with a 374% increase in year-on-year UK sales at art supplies store, Hobbycraft.

There's a lot here for kids to do (neat ideas including an End of Year Memory Book), but if you're a parent, you'll want to partake in this with your family anyway.

It has proved so popular that Vucajnk also released a coloring ebook based on woodland creatures. This isn't like the iPad coloring apps, however: it's a 14-page PDF to print at home – which isn't bad for $4.99 (plus VAT)!

Something for the Kids: Coloring Pages Blog

Blog Coloring Pages

Take a look at this easy-to-navigate archive site and you'd be forgiven for thinking it's aimed just at children. You'll see layouts of familiar characters, with sections devoted to Disney, Spongebob Squarepants, and Angry Birds. Yes, youngsters will take joy from coloring Tinkerbell, but many of the pages seem to be equally designed for those who want a bit of nostalgia.

Here you will come across Dr. Seuss, Star Wars... and the original Alvin and the Chipmunks (not these creepy CGI pretenders to the crown)! By the time you reach Smokey the Bear, you'll be convinced that this is a collection for all ages.

The nature of the beast means the designs themselves are far from challenging. Certainly, they're not as intense as some provided from other sites on this list. Nonetheless, it's pleasing to color in Mario, Tigger, or Bambi. If you're specifically searching for something more difficult, there's a small but solid Zen zone.

GI Joe might be a surprise addition, but it's still a treat to see pages made for national holidays like Easter and Christmas, as well as a Breast Cancer awareness section.

Stay Between the Lines

The press might be calling coloring for adults a simple fad, but actually, it has legs. Once everyone gets obsessed, it's something you can return to whenever you've had a bad day and come home looking for a distraction from the worries of life.

What do you think? Is it a trend that can turn into your adult hobby? What's your favorite site to get free printable layouts?