But that’s not the only data Spotify gets. If you really want to know what Spotify knows about you, then you need to read its privacy policy, which runs to 4,500 words. “I think they can use much clearer language,” says Pat Walshe, a data protection and privacy consultant who has researched Spotify’s use of data. “They can be more concise, they can lay it out better.”

Broadly, the rest of the data Spotify has about you is information you give it when you’re creating an account. You can tell it your username, email, phone number, date of birth, gender, street address, and country. If you pay, you’ll also give it your billing information. The company’s privacy policy also says it can get cookie data, IP addresses, the type of device you’re using, your browser type, your operating system, and information about some devices on your Wi-Fi network.

It can also get “motion-generated or orientation-generated mobile sensor data” from your device’s accelerometer or gyroscope. If you use its “Hey Spotify” voice controls, then it can also access these recordings.

Spotify can get extra information about you from other companies and services. If you log in with Facebook, for instance, it can “import your information” from there, including a Facebook user ID. Other “technical service partners” provide Spotify with data that puts IP addresses onto maps to know what city and state you’re in.

Spotify’s Ad Machine

The data that Spotify collects is not uncommon—other apps and services you use collect a lot more. But Barletta says the “most powerful thing” about Spotify is that it feels a lot more private than Facebook or other social media platforms, because you’re feeding its algorithms in a different way. “You can’t upload anything, you can’t have conversations,” he says. You are not sharing photos, videos, or messages. But, despite this, Spotify still knows how you think and feel.

It’s this behavioral data that helps Spotify go big on personalization. Its privacy policy says it can use your data for personalization, troubleshooting, developing new features and technology, marketing and advertising, research, and for other legal reasons. Many of these personalization features are likely to involve systems that recommend new music and playlists to you.

But there’s also Spotify’s advertising business—something that’s increasingly linked to its burgeoning podcast empire. The company’s privacy policy says it works with “advertising partners” to share data and work out what your “interests or preferences” are. “We may obtain certain data about you, such as cookie id, mobile device id, or email address, and inferences about your interests and preferences from certain advertisers and advertising partners that allow us to deliver more relevant ads and measure their effectiveness,” it says. The more “relevant” an ad is, the more likely it is to attract a higher price.

Spotify’s advertising documents show how ads can be targeted at your mood and what you are doing. Like electronica? Brands can target ads at the genre. But if you’re into folk, the ads probably won’t be the same. Listening to a “romance” playlist on a Friday night? The ads may be very different to your Sunday morning “road trip” playlist.