2018 was a horrific year for Facebook, marked by a series of scandals over data protection and privacy and concerns that the leading social network had been manipulated by foreign interests for political purposes.

Despite the scandals, Facebook revenue and user numbers have continued to grow.

Making ads relevant, and less annoying, involves understanding people's interests, according to Zuckerberg.

Facebook uses "signals" such as pages users "like" and what they share about themselves to target advertising.

"Sometimes this means people assume we do things that we don't do," Zuckerberg said of the business of supporting the social network with targeted ads.

"For example, we don't sell people's data, even though it's often reported that we do."

Selling user data would not only undermine essential trust in the social network, it would go against Facebook's business interests because rivals could use it to compete for advertising, he reasoned.

Facebook also provides users with controls regarding information used for ad targeting and lets them block advertisers, Zuckerberg pointed out.