London, England (CNN) -- Works by self-taught artists and those with schizophrenia and Down's syndrome are being presented in a gallery in Turin, brought together under the umbrella of "Outsider" art.
Usually taken to mean art created outside the bounds of official art production, outsider art takes in work made by the ill, insane, or unschooled.
Also grouped within the term are works of art created by prison inmates or those in captivity.
The Museum of Everything, a touring gallery of Outsider art which first opened in London last autumn, is stationed until the end of August at the Pinacoteca Agnelli in Turin, before returning to London later this year. It contains an unparalleled collection of Outsider or "Brut" art.
Art Brut (raw art) was first coined by the French artist Jean Dubuffet in 1945 and was later translated into English as Outsider art.
The definition of the term can be very broad, which is why the founder of the Museum of Everything, James Brett, decided to give it its inclusive name.
"The more I do it, the more I feel uncomfortable about the using the term Outsider art," he told CNN. "It's based on an assumption of what's inside and outside. It seems now quite arrogant."
The Museum of Everything is an attempt, Brett said, to show the work in a different light and to underline its influence on "official" contemporary art and pop culture.
Musicians including Australian Nick Cave and ex-Pulp front man Jarvis Cocker, and artists such as UK Turner Prize-winner Grayson Perry and Sir Peter Blake, gave their thoughts on particular works in the museum for mounted wall texts.
Cocker first heard about Outsider art while studying at Central St. Martin's College of Art and Design in London. In 1999 he made a three-episode television series that looked at famous examples of Outsider art.
"The idea of people creating for the sake of it rather than having lots of theories appealed to me. There is a creative impulse inside everybody, even if it finds its way out in strange ways," wrote Cocker in the Museum of Everything's exhibition catalogue.
Brett told CNN: "It's art by people who either don't consider themselves as artists, who are doing something out of an impulsive need to create."
"Or they consider themselves artists but somehow are out of the commercial artistic loop. It's more about connecting to a wider idea of what being creative is," he added.
The museum contains works by American Henry Darger. His life's work, "In The Realms of the Unreal," a fantasy manuscript about a magical world populated by fearless little girls, was only discovered at the end of his life in the 1970s.
Darger obsessively returned to this story about girls warring with evil adults throughout his life.
It was discovered shortly before his death in his tiny Chicago apartment.
Other works in the show include sculptures from Indian artist Nek Chand's garden in the city of Chandigarh in northern India.
In 1958, the roads worker cleared a patch of jungle to house sculptures that he made out of recycled waste material.
Now spanning several acres, it is filled with sculptures of people and animals.
The show also features work made by artists with severe handicaps, such as late American, Judith Scott.
Deaf and with Down's syndrome, Scott did not speak: she communicated instead via a series of hanging sculptures that she made out of layers of yarn, wool and thread.
"The Museum of Everything is much more about creativity than about art with a capital A," Brett told CNN. "It's a creative art that has given these people expression."
Interest in Outsider art has been growing steadily since the 1970s and, thanks to initiatives such as the Museum of Everything, is reaching an ever wider audience.
In 1979, English curator and dealer Victor Musgrave staged the first exhibition of Outsider art in Britain, at the Hayward Gallery in London.
He and partner Monika Kinley's extensive collection of was gifted to the Whitworth Art Gallery in Manchester earlier this year. Works from the collection are currently on view at the gallery as part of an exhibition called "Intuition."
Bryony Bond, who curated the show, said that the importance of Outsider art lies in its influence on contemporary art production and the way it challenges notions about what art is.
She told CNN: "I think, historically, the difficulty with Outsider art has been that it's hard to study -- you can't follow its art historical development.
It's a very individualistic type of expression. But that's part of the joy of Outsider art, that it has this freshness and honesty about it."
Though defined as art created outside the mainstream art world, examples from the genre can now be seen in major museums across the world. They are celebrated for their visual dynamism and the often heartbreaking stories that underpin them.
"Contemporary art and the market are very much related," Brett told CNN. "And as a result art has become very commodified.
"Whereas these guys tend to be much more truthful," he said.