Facebook CEO Mark Zuckerberg wants you to know that your data is important to his company. In a Wall Street Journal op-ed published Thursday evening, Zuckerberg laid out why Facebook collects data to use for advertisements, and how it lets you control that information.

The op-ed is meant to explain how and why Facebook collects information about its users : It lets the company sell ads and keeps the service free to consumers.

Zuckerbergs op-ed comes at an important moment. In a recent Pew Research Center survey, 74 percent of Facebook users said they had no idea that the company categorizes their interests based on their actions on the social network.