Internet users have been left shocked after a woman revealed what you need to do to find all the information Google has stored about you.
I think we've all pretty much come to accept by now that our various devices know a whole lot about us.
Most of the time they have our names, addresses, phone numbers and bank details stored and ready to go, and we've all seen the jokes about the 'FBI man' in the phone who listens to our conversations.
So it's less surprising - though still unnerving - these days when an advert pops up for something you've literally just been speaking about, but if you've ever wondered how some of the adverts you see are so accurate, you're about to find out.
In the clip, the TikToker heads to Google and searches for 'ad settings google'.
Once she's signed in, she's able to scroll down a list where Google shows her age, gender and even the languages she speaks.
The site also appears to show things she may be interested in, such as 'architecture' and 'audio equipment'.
This list can also be found if you head to your Google account and select 'Manage', click 'data and privacy' and select 'my ad centre'.
Google explains the categories it uses to show ads, including whether or not you're in a relationship or a parent, your education, your industry and even whether you're a homeowner.
To help personalise your apps, Google can use data from its sites and apps, including the general location you're in when you're using them.
It's quite alarming to see how much information the search engine has stored, especially if you don't ever remember handing it over, and the clip has been flooded with comments from people who were surprised to learn just how much Google knows about them.
"It's scarily accurate," one unnerved viewer wrote.
The information wasn't quite right for everyone, with one person admitting Google thought they were '44+' when they were really 19, but for many people it hit the nail on the head.
If you're not sure you want to be targeted with personalised ads any more, you can turn them off and adjust your privacy settings on your Google account.
The site explains: "Your account info is private to you, but you can share some of it or make it visible to others on Google services. Based on your settings, Google uses your data to personalize your experience."