Vox Media, home of The Verge, SB Nation and Polygon, made its name catering to niches like tech, sports and gaming. But now it wants to show it can do general news.

Vox.com officially launched Sunday night, three months after parent company Vox Media snagged high-profile Washington Post journalist Ezra Klein to run the site. Sponsored by GE and The Robert Wood Johnson Foundation at launch, Vox.com marks the latest step for Vox Media as it aspires to establish itself as digital heir to Time Inc.

"General news is an obvious category for a media company to cover," said Vox Media CEO Jim Bankoff. "It's a big category and something people care about and is established. And there's a lot of audience there. There are big pockets of audiences and advertisers who may have heard of Vox Media previously, and some have heard of us now."

Originally a collection of sports blogs running on SB Nation, Vox Media rebranded in 2011 with the launch of tech news site The Verge. A year later the company introduced a video-gaming site Polygon, and in 2013 acquired the Curbed network of sites to add real estate, food and shopping properties to its portfolio. Those six sites totaled 26.8 million U.S. unique visitors across desktop and mobile web in February, according to comScore.

Vox.com marks Vox Media's seventh brand, but the first it has built since 2012.

Rather than go dark for months then emerge with a full-fledged site -- like Nate Silver did ahead of FiveThirtyEight's launch last month under ESPN -- Vox Media's product team and the Vox.com staff has taken an experimental approach to rolling out the site.

"This is a very phased launch," said Mr. Klein, who co-founded the site with his former Washington Post colleague Melissa Bell and former Slate writer Matthew Yglesias.

Mr. Klein officially joined Vox Media on February 3. On March 9, Vox.com went up with a video and faux Q&A introducing itself as "a general interest news site for the 21st century." It carried the tagline, "Understand the News." Over the following month, the Vox.com team -- which now numbers more than 20 people -- got its feet wet by posting video interviews with transcripts.

Video will be an important content format for Vox.com. "This next phase is, I think, the beginning of the 'explain the news' phase, which is our core mission and we'll have products rolling out that speak to that," Mr. Klein said.

'Card Stacks'
To better explain the news, Vox.com is trying a new way of presenting information on topics in what its calling Card Stacks. The card metaphor came after the founding team started playing with the idea of what it means to provide context to the news. "We had a cool idea that context is a consistent layer of where you are in the site, and card stacks pop up and are easy to flip through," said Vox Media's chief product officer Trei Brundrett.

Wherever someone is on Vox.com, a swipeable card stack can pop up to annotate what is on that page with contextual information typically sourced from previous stories.

"I think that the great waste in journalism is everything a reporter has done before today or the last issue of publication," Mr. Klein said. For example, he has been covering Obamacare since before it was called Obamacare, when it was a whitepaper Senator Max Baucus published in late 2008. "I've written thousands of articles and blog posts and tried to understand the bill and the law. But almost all of that work is not accessible to readers," he said.

"Card stacks are a way to try to take all of that work and distill it into something usable for readers," Mr. Klein said. The card stacks will be collected into pages that people will be able to check out to study up on a topic. These can be compared to Wikipedia entries -- minus the user-generated aspect -- but Mr. Klein likened them to WebMD records that are created and maintained by medical experts. "We have a page on Obamacare kept up by professional Obamacare reporters," he said.

Vox.com's focus on explaining the news has been picked up by other Vox Media sites like The Verge. While the tech news site has always made a point of providing context for readers, the product work done on Vox.com will help The Verge in beefing up that area of its coverage.

Explaining the news
"I do think that context is a huge deal. Have we found the best ways to deliver context to readers in news? I don't think we've done that, and I think that Vox is going to move the ball forward," said The Verge editor-in-chief Joshua Topolsky. "I think we're going to be able to take what they've done and continue to move it as a company, as Vox Media takes the technology and spreads it throughout the verticals."

Card stacks also represent a new ad product for Vox Media. "If there's a card stack on Obamacare or Bitcoin, advertisers can integrate directly into those topic areas," Mr. Bankoff said, adding that any sponsored cards would be clearly labeled as such.

As Vox Media looks to build a self-sustaining company from the $73.2 million it has raised in funding, Vox Media's product team has made a point of developing editorial products with advertising in mind. "During the latter part of last year, we started doing this thing where for any product we're building, advertising is day zero," Mr. Brundrett said.

Like Yahoo with Tumblr, Vox has spun off a version of its publishing tool, Chorus, specifically for brand advertising. Called Harmony, the ad toolkit offers a way for the company's in-house agency Vox Creative to create the full-screen, magazine-like custom ads that Vox Media released last summer.

As with Vox.com and its underlying technologies, Vox Media remains a work in progress. The company has added four sites in the last five months and is now turning toward expanding on what it has. "I'm on the record to say we don't have any major new brands in development," Mr. Bankoff said.