Groupon unveiled Personalized Deals, a new service that tailors each Groupon subscriber’s stream of daily deals to their personal preferences and buying history. Personalized Deals are live in Chicago, San Francisco, San Jose, Los Angeles, New York, and Seattle, and are slated to launch across Groupon’s more than 80 North American markets within months.

Each subscriber’s deals will get more relevant over time as they share information and form buying patterns, and as Groupon’s deal offerings expand. Subscribers will see no change to their Groupon interface. They’ll still receive a deal per day via e-mail, available for a minimum of 24 hours.

“The number one request from our customers is for more relevant deals,” says Andrew Mason, Groupon’s founder and CEO. “After six months of product development, we’re excited to deliver. This is the biggest thing we’ve ever done, and we think one day people will think of the original, nonpersonalized version of Groupon the way we think of the steam engine.”

Customizing deals allows Groupon to run more deals for businesses that are located outside of city centers, that cater to niche audiences, or that aren’t seeking the heavy volume traditional Groupons deliver. Sending different deals to different users also helps address the overwhelming demand from merchants to be featured on Groupon.

“Interest in Groupon is so high we can only feature one out of eight businesses that contact us,” Mason says. “Personalized Deals opens Groupon up to more merchants, who until now have been forced to look elsewhere to find new customers.”