Yahoo: What Makes You Click? "Yahoo C.O.R.E"

Visualizing How Yahoo! Serves Up 13,000,000 Unique Story Combinations, Every Single Day
Ever wondered how Yahoo! decides which stories to put on its front page each day? Or why your Red Sox team scores or daily omg! fix usually appears up front?
That’s because the Yahoo! page you see each time you visit is likely different than the person sitting next to you. In fact, more than 13,000,000 personalized story combinations are delivered every day on the Today Module (the little box at the top of our homepage displaying featured stories), and it happens within milliseconds of you visiting our site. The minute you log into your Yahoo! account, personalization goes a whole level deeper.
Today we unveiled an innovative way to visualize the magic that makes it all work, and what it means for you.
Go ahead and click here to check it out. The tool is populated in near real-time, so you can discover what the most popular story is, right now. For instance, you might be interested to learn that today more than 12 million people have seen an article on the $26 billion mortgage foreclosure deal reached between the U.S. government and leading banks. Or that 92 million people saw a video on a test driver’s close call with a deer while filming a commercial.
Yahoo! creates uniquely meaningful experiences for every single person, at this scale. How? It’s simple, really. We do it with deep science and great engineering.
The Magic Behind It: C.O.R.E.
Initially developed within Yahoo! Labs, the award winning science and research group within Yahoo!, C.O.R.E. (Content Optimization and Relevance Engine) is an innovative suite of technologies that allows us to feature the stories most likely to be interesting to you.
Today, C.O.R.E. powers content on many Yahoo! properties, including Yahoo! News and the Today Module. There, editors write and gather the most important and engaging stories of the day, and C.O.R.E. determines how stories should be ordered, dependent on each user. Similarly, C.O.R.E. figures out which story categories (i.e. technology, health, finance, or entertainment) should be displayed prominently on the page to help deepen engagement for each viewer.
What’s unique here is not just the innovative C.O.R.E. algorithms that crunch this amount of data all day, every day - but that it’s also the perfect marriage of deep science and a world-class editorial team.
Editors use C.O.R.E. and their editorial judgment to ensure that important stories are front and center. For example, Yahoo! editors made sure that the news of Osama Bin Laden’s death was on everyone’s page the moment the news broke. An algorithm couldn’t have done that.
So how does C.O.R.E actually work?
C.O.R.E. measures how often users click on stories overall and within different segments of the population. In just a few visits to, you’ll start to see tailored content appear just for you. And the more time you spend, the better it gets.
Since C.O.R.E. was implemented in 2008, people click on the Today Module four times more often than they used to – in fact, more than 1 billion times per month! To put that in context, every eight minutes C.O.R.E. registers more clicks on the Yahoo! homepage than there are words in the entire English language.
Rather than list out the millions of possible combinations, we created an interactive visualization that allows you to experiment with C.O.R.E. You can explore the day’s most popular stories or put yourself in someone else’s shoes and see Yahoo! through their eyes.
Go behind the scenes and drill into the data that powers the personal content experiences of 700 million users here:
Steven Lyons,
Sr. Product Manager, C.O.R.E.