To download the complete version of "The Story So Far: What We Know About the Business of Digital Journalism," a new report on digital news economics from the Columbia University Graduate School of Journalism, click here.

Huffington often says that aggregation benefits original-content producers as much as it does the aggregators. The story of a recent blog post on New York magazine’s site makes for a good illustration.

At about the time that Huffington and Armstrong were visiting the school in Brooklyn, Gabriel Sherman, a contributing editor to New York, was nailing down a scoop. Under the headline “Going Rogue on Ailes Could Leave Palin on Thin Ice,” Sherman reported that Roger Ailes, the head of Fox News, had warned his paid commentator, former Alaska governor Sarah Palin, not to go forward with her video accusing the media of “blood libel” in the way they portrayed conservatives after the shooting of Arizona representative Gabrielle Giffords.

The story required at least three days of reporting and editing work. The facts had to be bulletproof. The post went live on nymag.com’s Daily Intel column at 7:57 p.m. on March 13.

The next morning, an editor for the Huffington Post spotted the item and wrote a rendition of it for that site, publishing at 8:27 a.m. Huffington Post played by the rules: It credited Sherman by name and gave nymag.com a link at both the beginning and the end of the item. What Huffington Post took from Sherman’s post—237 words, or about half the original length—would be justifiable under almost any definition of copyright.

The power of aggregation soon became clear: The original Sherman post drew nearly 53,000 readers on nymag.com, and about 17,500 of them came directly from the links on Huffington Post. Smaller numbers of readers came from hotair.com, which is part of a network of conservative websites and publications; and from Andrew Sullivan’s popular blog, The Daily Dish. All told, three-fourths of the traffic to Sherman’s story came from other sites. The item also drew more than 130 reader comments on nymag.com, which is far higher than what the typical blog post gets.

The real winner, though, was Huffington Post. Its aggregated version of the item got more than 2,000 comments. Comments are not a perfect proxy for traffic, but it appears that the Huffington Post item got a much bigger audience for its post than the original New York item, for a fraction of the cost.

As this example shows, links from other sites or search engines are among the cheapest and most efficient ways to bring in new users. Even the largest news suppliers, such as Time.com or CNN.com, appreciate what top billing on YouTube or Google News can do to increase traffic and advertising revenue. “There are ways you can deliver better ad results, but you can’t do it if you focus on your own content only and not others,” Scout Analytics vice president Matt Shanahan says. He adds that when sites promote each others’ content, they create more engaged audiences through additional page views and commentary. “The advertiser wants the audience,” he says. “And the audience wants the audience.”

News organizations have always blended material from a variety of sources by combining editorial content from staff, news services, and freelancers; adding advertising; and then distributing the package to consumers. In the digital world, news aggregation is not so different. It involves taking information from multiple sources and displaying it in a readable format in a single place. Digital aggregation businesses can be successful when they provide instant access to content from other sources, and they generate value by bringing content to consumers efficiently.

The cheapest way to aggregate news is through code and algorithms, with little or no human intervention. The way an individual story is displayed throughout the day is determined automatically, typically according to how recently the article was published and how popular it becomes. Aggregation is slower and more expensive when it becomes “curation,” involving humans in the filtering and display processes.

Google News belongs to the most basic aggregation category, called “feed” aggregation, in which an algorithm sorts news by source, topic, or story and displays the headline, a link and sometimes a few lines from the original story. The costs are low.

Bill Grueskin, Ava Seave, and Lucas Graves are the co-authors of "The Story so Far: What We Know About the Business of Digital Journalism." Grueskin is dean of academic affairs at the Columbia University Graduate School of Journalism. Seave is a principal of Quantum Media, a NYC-based consulting firm. Graves is a PhD candidate in communications at Columbia University. For further biographical details, click here.