It’s a little creepy right?
You’re scrolling through some new social media app you just downloaded.
You haven’t even finished setting up your profile.
And bam.
It suggests connecting with your main Google account.
It knows your name and your profile picture is right there.
How in the world did it know? It’s not magic.
It’s just a web of connections online that we normally agree to without a second thought.
Let’s break down how this stuff actually works in 2025 because it’s gotten pretty clever.
The Most Obvious Way: You Clicked “Sign in with Google”
This is the big one. It’s the front door you opened yourself.
When you see that convenient “Sign in with Google” button it seems so easy.
No need to remember another password.
But when you click that you’re creating a direct link.
You are giving that social media site permission.
Permission to talk to your Google account.
A pop-up window appears.
It lists all the things the site wants access to.
Typically your name, email address, profile picture and maybe your contacts list.
Most of us just click “Allow” without really reading it.
That’s it. You’ve given them the keys.
The social media site now has a special token.
This token proves to Google that it’s allowed to ask for your info.
It is this action that creates the most direct connection possible.
There’s no guessing involved here you gave them a formal introduction.
The Sneaky World of Digital Breadcrumbs
Okay so what if you never used Google to sign in?
How would a social media site know my google account then?
Well the internet has a long memory.
This memory is made of little files called cookies and trackers.
The Cookie Connection
Cookies are just small text files websites store on your browser.
Some are for remembering your login.
Others are for tracking you across different websites.
Google has a huge advertising network.
This network places cookies on your browser when you use Google Search or Gmail or YouTube.
Then, you visit a social media site.
That site probably has Google’s advertising code on it.
That code can read the Google cookie already in your browser.
Now the site knows a Google user with a certain ID just visited.
It’s like you’re wearing a name tag from a Google event and you just walked into their party.
They don’t know your password, but they know who you are in the Google world.
What’s a Tracking Pixel Anyway?
This is even sneakier.
It’s a tiny, often invisible 1×1 pixel image on a webpage.
When your browser loads that tiny image it sends info back to a server.
Info like your IP address and that you viewed a certain page.
Social media sites and Google’s ad network use these all over the place.
They build a profile of your browsing habits.
And they can match your activity on the social site with your activity on other sites where you’re logged into Google.
Your Browser Is Basically a Snitch
Your web browser gives away a lot about you.
Every browser has a sort of unique “fingerprint”.
This isn’t a real fingerprint of course.
It’s a combination of details about your setup.
Your operating system (Windows, Mac)
The browser version you’re using
Your screen resolution and color depth
The fonts you have installed
Your language settings
The plugins you have installed
All these little things together make a profile.
A profile that’s pretty unique to you.
If you are logged into Google in one tab.
And then you open the social media site in another.
The site can see your browser fingerprint and make a really good guess.
It can guess that the person with this fingerprint is the same person logged into that Google account.
It’s not a 100% lock but it’s very accurate.
The Mobile App Universe and Shared Code
Things get even weirder on your phone.
Apps are not as separate as you think.
Many developers use what are called SDKs.
Software Development Kits. Think of them as pre-made blocks of code.
It helps them build apps faster.
Google offers a lot of popular SDKs for things like ads, maps and analytics.
When a social media app uses Google’s ad SDK for instance.
It’s basically inviting Google’s code to run inside its own app.
This creates a bridge for information to be shared.
The Role of the Google Advertising ID
Your smartphone has a unique ID just for advertising.
It’s called the Google Advertising ID (GAID) on Android.
Or the Identifier for Advertisers (IDFA) on Apple.
You can reset it but it’s there by default.
This ID is shared among the apps on your phone.
So the new social media app can see your phone’s ad ID.
Google also knows that ad ID belongs to your Google account.
So the app tells Google’s ad system “Hey, GAID 12345 is using me”.
Google says “Got it. GAID 12345 is Bob’s Google account”.
And just like that the connection is made.
Frequently Asked Questions
So, how would a social media site know my Google account if I never used Google to sign in?
They can still figure it out using other methods. The most common are third-party cookies from Google’s ad network that are on their site, and your browser’s unique fingerprint which they can match to your general web activity. If you’re on a phone, they can use your phone’s unique advertising ID.
How would a social media site know my Google account just from me visiting their page?
Just by loading their webpage, your browser can give them clues. Their site likely has trackers that can read cookies left by Google from your other browsing. This tells them that a known Google user has arrived on their doorstep, even if you don’t log in or do anything.
Can I stop a social media site from knowing my Google account?
You can make it much harder for them. Regularly clear your cookies and browser cache. Use your browser’s “private” or “incognito” mode. Use different browsers for different activities, like one for your Google account and another for random browsing. And most importantly, read the permissions screen carefully if you ever do use “Sign in with Google”.
Is it legal for a social media site to know my Google account details?
Generally speaking, yes. When you sign up for these services, you agree to their Terms of Service and Privacy Policy. Buried in that long legal text is usually your consent for them to use cookies, trackers, and other technologies to collect data for advertising and functionality.
Does using a VPN stop them from knowing my Google account?
A VPN is great for hiding your IP address and location. But it doesn’t stop cookies, tracking pixels, or browser fingerprinting. If you’re logged into Google in your browser, a VPN won’t hide that fact from the websites you visit. It helps with one piece of the puzzle, but not the whole thing.
Key Takeaways
You Give Permission: The easiest way they know is because you used the “Sign in with Google” button and clicked “Allow.”
Web Trackers are Everywhere: Cookies and tracking pixels from Google’s ad network are on millions of sites, and they link your activity back to your Google profile.
Your Phone Talks: On mobile, apps can share your unique Advertising ID, creating a clear link between the social media app and your Google account.
Browsers Have Fingerprints: The unique setup of your browser can be used to identify you across different websites.
It’s a Trade: We trade bits of our privacy for convenience and “free” services. Being aware of how it works is the first step to taking back a little control.
