What Google knows about you

Google is the undisputed leader in the tech giants' race to accumulate user data, thanks to its huge array of services, devices and leading share of the digital ad business (37% to Facebook's 22%). It likely knows everything you've ever typed into your browser’s search bar and every YouTube video you’ve ever watched.

• But that's just the beginning. It may also know where you've been, what you've bought and who you communicate with.

What Google collects:

• The terms you search for.
• The videos you watch.
• Voice and audio information when you use audio features.
• Purchase activity.
• People with whom you communicate or share content.
• Activity on third-party sites and apps that use Google services.
• The ads and content you view on Google's sites, as well as interactions with that content.
• Chrome browsing history you've synced with your Google Account.
• Location data, which Google can either gather directly via GPS data or infer from other sensors and data, including IP addresses, nearby Wi-Fi routers and Bluetooth beacons.

What Google doesn't collect:

• Google Docs data from business customers who use the paid enterprise version.

• Internet traffic from its Google Wi-Fi home routers.
• The company used to use the content of emails in Gmail to choose ads to display, but it no longer does so, saying its other data is more efficient.

The big picture: Google isn't just its namesake search service. It also gets lots of data from its Chrome browser, as well as from YouTube, devices running its Android operating system, the Google Assistant, and Google Maps, along with hardware products like Nest and Google Home.

• Even those who don't actively choose Google's services still probably have a fair amount of information landing on its servers. It's a huge player in digital advertising, with widely used tools for serving ads and providing analytics.
• Google's privacy policy (which you probably haven't read) offers a good overview of its practices, while a separate tool allows users to see what information the company has been collecting.

Between the lines: A study last year by Vanderbilt University's Douglas Schmidt found that Google and Chrome are sending plenty of data to Google even without any user action, including location data (assuming a user hasn't chosen not to share such information). And nearly half the data came from people's interaction with Google's services for advertisers, as opposed to consumers directly choosing to use a Google service.

• Google challenged some of the study's points and highlighted some new privacy tools, but Schmidt says his key findings remain the same.
• "You can fiddle around with a few knobs and make yourself feel better," Schmidt tells Axios. "I don't think much has changed."

Location, location, location

Location data raises some of the thorniest issues for Google users.

• Letting Google track your location can help it learn where you work and live, predict when you need to leave the house and even tell you when you need an umbrella.
• At the same time, such data hands Google a picture of our lives so incredibly detailed that it will make many people uncomfortable.
• That picture will only grow in scope as Google expands the array of hardware products, from Nest cameras and thermostats to Google Home Hub and Pixel, that point more cameras and microphones at your life.

What else?

In addition to everything Google collects via its services, Google search aims to be a repository for all the world's information. That means there's a mountain of information accessible on Google because someone, somewhere in the world has put it online.

• If embarrassing pictures from your high school yearbook or information about your DUI is posted online, Google will help people find it. (An exception is for those in Europe, where the "right to be forgotten" lets people request certain info be removed.)

What can you do?

There's a fair amount you can do to at least limit what Google knows about you.

• You can use another search engine, like Microsoft's Bing or the even more privacy-centric Duck Duck Go.
• Choosing an iPhone alone won’t get you out of Google's grasp. Google pays Apple billions of dollars each year to be the default search engine on the iPhone, iPad and Mac. You can change that default, but relatively few people do.
• On the browser front, you can choose to use Firefox or Safari, or also use Google's Chrome in private browsing mode, or choose something like the privacy-oriented Brave.
• You can choose not to stay signed in to your Google account when using its services. Outside of just not using Google products, this is probably the single biggest step you can take to hide yourself from the company — but it means you will need to log back in every time you want to, say, check a Gmail account or read a Google Doc.
• And you can go here to see what Google does know about you. Just make sure you are signed in (and check all your accounts if you have more than one).
• You can also clear your Google history, something Facebook has promised users but has yet to deliver. Clearing your history means Google won't use the information to personalize your Google experience. Deleting it is another matter.

Whatever steps you take, it can be incredibly tough to block out Google entirely, even if you want to, as Gizmodo's Kashmir Hill found, because Google's services power so many others. If you really wanted to shut out Google, you'd also have to give up Uber, Lyft and Spotify.

What's next: Today, Google uses its vast trove of data mostly to target ads at us. Increasingly, it will apply the same resource to powering and optimizing the artificial-intelligence-based services that it and its rivals are building.

Go deeper:

• Special report: Inside the mass invasion of your privacy
• What Facebook knows about you