It was a "prank website that I made when I was a sophomore in college," Zuckerberg explained to a lawmaker last month.
The new dating feature, Zuckerberg said this week, "is for building real long-term relationships, not just hookups," and he said it could be life-changing for the more than 200 million Facebook users who list themselves as single.
In 2013, Facebook and Cornell University researchers pulled data on 1.3 million users to try and predict whether couples would break up within 60 days of Facebook-announcing their relationship.
The love-seeking singles of Facebook's new dating service, privacy experts say, may not be prepared for what they'll encounter: sham profiles, expanded data gathering and a new wave of dating fraud.
Facebook -- under fire for viral misinformation, fake accounts and breaches of trust -- said this week it will soon offer a new dating service designed to help its users find love, giving the world's largest social network a uniquely intimate vantage point on its users' romantic desires and personal lives.
Company officials said they won't use dating-service data to inform ad targeting at the outset.
But marketing experts said they're skeptical that Facebook's promise will last.
Facebook will log interactions on the dating site, keep a record of everyone a user likes or rejects and gather other data necessary for the service to work, officials said.