Here's the story of another Web destination popular with a hardcore audience of millennials but struggling with the question of how to introduce digital advertising to users critical of almost anything corporate. We've seen it play out time and again, and now it's Imgur's turn to make the jump from a free-for-all community to a legitimate Web advertising player.

The startup is taking its promoted posts out of beta this summer after a few test runs with brands like eBay.

Imgur is a kind of Reddit for images, where people post photos, GIFs and memes, and the ones with the most votes rise to the top. It was created to be an easy way to post images online and share them anywhere on social media, and it's become an unofficial image-hosting backbone for many of Reddit's image-centric forums.

Imgur has more than 150 million monthly active users, a mostly young, largely male audience with a reputation for being commercially skeptical. That's why Imgur is slowly introducing sponsored posts and carefully crafting branded submissions, all with the goal of avoiding a fiery backlash.

"We work with the advertiser to develop content that would fit well with the community," said Steve Patrizi, Imgur's vp of marketing and sales. "So, users perceive the content coming from brands as something that enhances the experience."

That may be easier said than done, but so far, Patrizi said, results have been compelling. Users who view sponsored posts on Imgur give a thumbs-up nine times out 10.

This summer, eBay has been a main marketer on the site, with a few posts that took advantage of Imgur's storytelling style. The online auction site posted GIFs and photo albums that, for the most part, seemed well received, judging form the hundreds of comments.

"We worked with Imgur for several months to research the types of themes and items that were popular on site, and we worked with some Imgurians to source imagery that helped us tell the best stories," said Johnna Hoff, eBay's head of communications.

Imgur has an in-house creative team that helps brands make their posts, and brands that master Imgur basically master the Web—grasping the style, the language and the content that performs best.

"We're helping brands become citizens of Internet culture, not just a sponsor," said Imgur's Michelle Masek, head of communications.

In eBay's case, the company had posts with titles like "Tech Transformations That Happened In Your Lifetime," a gallery which started with the animated GIF (pulled from a video by BestReviews.com) shown at the top of this article and then showed examples of technology that evolved rapidly. Each example links to live listings of that product on eBay.

"Other companies who want to promote posts on imgur should take note, THIS is how to do it," one commenter wrote under eBay's post.It's the kind of post the Imgur crowd might like even if it weren't a paid placement.

Imgur says 75 percent of its audience is under 35, and 60 percent is between the ages of 18 and 24. Also, it's seen as a kind of male alternative to Pinterest, which skews female.

"Imgur has the highest composition of millennial males compared to any other mass-reach community," the company said in an e-mail detailing its user stats.

Patrizi described Imgur as a place for brands to reach the quintessential Web user, one who's into things like sci-fi, video games and geek culture.

"We started tracking the amount of time people are spending on these promoted posts, and it's 25 seconds a post," Patrizi said. "That's getting pretty close to the gold standard of TV advertising."

This summer, Imgur is getting ready to run more promoted posts, opening ads to more brands following the footsteps of eBay, which appears to have gotten the formula right.

"We've been extremely encouraged by what we've seen in the Imgur promoted posts beta," Hoff said. "It's been a collaborative effort across eBay, Imgur and the Imgur community to understand the imagery and stories that resonate."

Below is a look at another eBay ad, this one called "It'll be worth something, someday."