It’s the season of gift giving, and while some gifts may become cherished heirlooms, others will likely wind up at Goodwill not long after the holidays.

Then what happens to them, and all the other stuff we accumulate?

That is the topic of Adam Minter’s new book: “Second Hand: Travels in the New Global Garage Sale.”

“In many ways, the book becomes a book about consumption and our attachment to our things,” Minter said. “But it also becomes a story about the limits of how we can reuse.”

“Second Hand” follows from Adam Minter’s first book, “Junkyard Planet: Travels in the Billion Dollar Trash Trade.”

That book -- about industrial-scale recycling -- got such an outpouring of letters from readers about their experiences with the reuse and resale of their personal stuff, that he decided to write about that.

It’s a global and mostly untracked, secondhand economy.

“It's sort of this hidden industry, but especially in emerging markets, in places like the African continent and in parts of Southeast Asia, secondhand is the economy. And yet we really don't have any way of measuring that because governments and businesses and policymakers are really focused on new, and how much are we consuming new and producing new for the retail trade,” Minter said.

Minter travels throughout the world to track down where our stuff ends up. He travels with employees of Empty the Nest, a home clean-out service, and Gentle Transitions, a move manager, both in the Minneapolis-St. Paul area.

“We really got into some fairly emotional situations because there's this almost primal urge for people to see that their stuff is reused or their parents’ stuff is reused. And yet more often than not, they were finding out that … there's not enough people out there who want it,” he said.

He also went on home clean-outs in Japan and found hoarding is a national problem, stimulated by the post-war boom years and a love of the new in design and fashion.

“Hoarding isn't just something specifically American, but there seems to be something inherently human about it. We all want to do it, and we all want that space that we have to store this stuff,” he said.

In the U.S., the accumulation of both wealth and ever larger houses coincided over the past 50 years. The desire to fill those bigger spaces with stuff led to an explosion of storage facilities.

“You have this combination of affluence and space in the United States that combined to create this phenomenon that simply wouldn't have existed at other times,” he said.

What Minter also finds is a complex and sophisticated system of sorting through discarded stuff. Clothing at Goodwill, for example, is categorized by brand desirability. Torn or soiled clothing might be sold to ragmakers, to be used “for everything from wiping down counters at bars and restaurants to wiping up leaks at oil pipelines.”

On average, Minter said, only about one-third of the merchandise that goes out to the retail floor in American thrift shop sells. That stuff is then repackaged for an export market.

Minter’s book coincides with the decluttering trend promoted by Japanese celebrity declutterer Marie Kondo. However, Minter pointed out that the Japanese interest in decluttering stems from their smaller homes. They love buying new stuff as much as Americans do, Minter found, which is why they’ve “developed an extremely sophisticated secondhand economy that moves stuff through all kinds of levels of reuse, especially on the retail side.” And unlike Marie Kondo’s focus on clearing out the house, “in Japan, the decluttering and minimization movement really is much more focused on that ecological side of things.”

Minter also cites a report from Hamaya, a leading exporter of used electric home appliances in Japan, which tracks where Japanese goods end up: acoustic guitars go to Mali, electric guitars go to Nigeria, boomboxes to Afghanistan, thermoses to Madagascar, big chainsaws go to Nigeria, smaller chainsaws go to Cambodia, and so on.

Some of Minter’s characters didn't want their names used because in some cases, importing or exporting used goods is banned to protect domestic manufacturers. Nevertheless, used goods flow freely across international borders, and the repair and reuse industries contribute significantly to local economies.

But the book is also a story of the decline of families and communities and the burgeoning rates of loneliness. People hoard stuff but have no one to pass it onto.

In Japan, which has a shrinking population, Minter meets a Japanese woman who showed him her grandmother’s dozen kimonos. The woman was selling them because she had nowhere to put them.

“This was letting go of objects that had defined what was left of her family. And I think every everyone who lives in modern societies has had that experience at some moment. And it is a social problem, it's a psychological problem, and it's a very human problem,” Minter said.

Of course we had to ask him: After traveling the world of stuff, what will he be giving loved ones this holiday season?

He says his gift giving is now focused on experiences, like a restaurant gift card or a night in a hotel.

“Let people enrich their lives and start spending more time with family instead of focusing so much on how we identify with our stuff,” he said.