For one of our earlier publications on r/MildlyInteresting, its moderator RedSquaree, said, "I think we've done an amazing job of curating a subreddit that is still niche despite being hugely popular."

"The content is roughly the same today as it was almost a decade ago. Most subs change (for the worse) as they grow, but we've kept things mild—just the way people want it," they explained.

It's hard to pinpoint what makes something 'mildly interesting' but as my colleague Innes highlight, there’s a certain theme running throughout the images: they depict things that go against the grain of what we consider as “normal” in everyday life. Or, they capture some bizarre coincidence that we would never have expected.

But RedSquaree, who has been looking over the subreddit for some time, thinks the main ingredient of the formula is ambiguity. They said, "Everyone probably has a slightly different interpretation or idea of what is mildly interesting." But they believe that the concept of relatability is most important—it has to be "nothing spectacular but something novel".

However, this can also make it difficult to moderate the content. As RedSquaree explained further, "Sometimes we see users post to r/MildlyInteresting first (because if they didn't, it would break rule 3 of our page). Then, they go on to crosspost to r/damnthatsinteresting. And we're thinking to ourselves, '/r/HolUp, it can't be both.'"

Researchers understand human curiosity as being linked to learning and information seeking. In terms of evolution, it makes sense for people to be curious about the world around them.

Professor Celeste Kidd studies curiosity and learning at the University of California, Berkeley where she runs the Kidd Lab. “Curiosity is the driving force behind everything we know,” she said.

Celeste’s research suggests we’re most curious when we feel uncertain about something. This could explain the popularity of r/MildlyInteresting!

"Uncertainty indicates that there’s valuable knowledge available," she highlighted. "By contrast, certainty indicates you know everything there is to know so there's no point in continuing to be curious because there’s nothing further to be gleaned."

This is sensible, she explains, because it guides us towards what is most useful for us to learn.

In uncertain times, curiosity can help us to focus on the most pressing issues. This could explain the growing interest humans show in fields like sustainability, the circular economy, and ethical data use.