Jan. 25 (UPI) -- Facebook founder Mark Zuckerberg explained and defended the social media network's business model in an opinion piece Thursday night amid growing accusations the company profits off users' personal information.
The chief executive of Facebook, which turns 15 next month, wrote in The Wall Street Journal he wants to run a free service anyone can use, but that requires the ability to sell targeted advertisements.
"People consistently tell us that if they're going to see ads, they want them to be relevant," Zuckerberg wrote. "That means we need to understand their interests. So based on what pages people like, what they click on, and other signals, we create categories-for example, people who like pages about gardening and live in Spain-and then charge advertisers to show ads to that category."
He added that online advertisements give users greater control over the type of marketing they see -- something radio, television and print can't offer.
"You can find out why you're seeing an ad and change your preferences to get ads you're interested in," Zuckerberg wrote.
In a typical business transaction, customers pay for services rendered. With Facebook and other social media sites, the services are free "and we work separately with the advertisers to show you relevant ads."
Critics have long said if a digital product is free, that means the user is the product being sold.
Zuckerberg was called to testify in Congress and European Parliament last year after a scandal that allowed political consultancy group Cambridge Analytica to access the personal information of 87 million users -- including Facebook's best guess at their political leanings. Thursday, he denied claims that Facebook sells user data.
"In fact, selling people's information to advertisers would be counter to our business interests, because it would reduce the unique value of our service to advertisers," Zuckerberg wrote. "We have a strong incentive to protect people's information from being accessed by anyone else."
Michael Kosinski, an assistant professor at Stanford University, balked at Zuckerberg's claim.
"[That's] like a bar giving away a free martini with every $12 bag of peanuts and then claiming that it's not selling drinks," she wrote in The New York Times last month. "Rich user data is Facebook's most prized possession, and the company sure isn't throwing it in for free."
Zuckerberg also dismissed claims his company's desire for engagement and traffic encourages more "clickbait" and inflammatory content to keep people coming back.
"Clickbait and other junk may drive engagement in the near term, but it would be foolish for us to show this intentionally, because it's not what people want," he wrote.
The Facebook chief added that artificial intelligence finds divisive and harmful content and removes it, although some slips through. He also said Facebook's permissions comply with the European Union General Data Protection Regulation. Britain's privacy watchdog fined Facebook more than $650,000 last year for failing to protect user data.