Firstly, I’m not against privacy or anything, just ignorant. I do try to stay pretty private despite that.
I wanted to know what type of info (Corporations? Governments? Websites??) Typically get from you and how they use it and how that affects me.
Actually police (and governments) don’t need to purchase your data. They can gather anything and everything from what people share publicly and constantly on social media. Countless numbers of people have been arrested because of what they shared publicly and the metadata included with that share.
If they need criminal info they have immediate access to it.
The concern isn’t that you do something wrong, it’s that the data that you put out there can be used against you in countless ways. Marketing, sales, and so on are the least of your worries. If anyone wants to threaten you, your loved one’s, or even trick you into thinking they are in a threat situation, most people don’t realize how easy that could be with the data they give away daily.
That’s why I said this:
They don’t need warrants for location data if it’s bought from a company that sells that data.
Whether or not it’s admissible in court is another question, though.