Stumbling upon a specifically tailored advertisement on your iPhone can be a bit disconcerting, and that's exactly what will happen if you let advertisers track your data. Some of you may appreciate more relevant ads in your apps, but the rest of you might consider this a straight-up privacy invasion. Luckily, there are a few things you can do to limit their reach to you on your iPhone.
Almost everything you do on your iPhone can be used by advertisers that take advantage of Apple's own ad platform or via their own system in web browsers. If you want to restrict these advertising companies from sending you "stalker" ads based on your interests and other information, keep on reading.
Apple's ad platform tracks a remarkable amount of contextual information to serve ads to you, including your name, address, age, gender, and location — and that's just the tip of the iceberg. It collects all kinds of device info, your App Store searches, the articles you read in Apple News, what you download, and most importantly, what you do in other apps such as Facebook, Instagram, and Safari.
Apple shares its information with advertisers who use the data to show you targeted ads in the App Store, Apple News, and Stocks. Unfortunately, while there is no way to stop Apple from collecting your personal data, you can stop advertisers from showing you targeted ads.
You can opt out of receiving location-based advertisements from advertisers using Apple's ad platform by disabling "Location-Based Apple Ads." Do this by going to Settings –> Privacy –> Location Services –> System Services. Next, toggle off "Location-Based Apple Ads," and you will no longer receive tailored ads based on where you are.
You could also disable "Location Services" altogether, meaning Apple would not receive location-based information at all, but this would also make it difficult to use apps that require your location such as Google Maps, Instagram, Safari, Uber, Twitter, Tinder, and more.
To limit ad tracking altogether, not just by location, go to Settings –> Privacy –> Advertising. Next, toggle on the "Limit Ad Tracking" setting. Although you will still see the name number of ads in the App Store and Apple News as before, they'll be less relevant now since you've opted out of receiving targeted ads.
If you tap on "View Ad Information," you can see that you're now opted out of interest-based targeting, but information about your specific device is still used to deliver ads to you in the right language, time zone, location, etc.
Even if you limit ad tracking and disable location-based ads for Apple's advertising platform, Apple still has a ton of your personal information saved, stored in your Advertising Identifier. Underneath "Limit Ad Tracking," you have the option to clear this data by tapping "Reset Advertising Identifier." Your identifier is replaced with a non-unique series of zeros to prevent others from serving you targeted ads. If you disable "Limited Ad Tracking," you get a brand new identifier.
All advertisers who use Apple's ad platform must stop sending you tailored ads. However, they could technically use another advertising platform with your Advertising Identifier as a basis, but that can get them in trouble with Apple, so you won't see this much.
Although Apple may honor your request to limit ad tracking on their advertising platform, that doesn't mean that advertisers on other advertising platforms must adhere to this in general. Any website you are directed to in Safari or in another app using the WebKit browser is capable of tracking your information, providing it to advertisers who then provide you with tailored ads.
To stop websites and advertisers from tracking your web browsing activity, go to "Settings," tap "Safari," then turn on "Ask Websites Not to Track Me." Now, every time a page loads in Safari or in a WebKit version in another app, Apple will add a request not to track you, and websites may or may not oblige.
Unfortunately, it's up to the website to honor any request, and many of them won't. That's why Apple removed the feature in iOS 12.2. There are better tools in Safari to limit tracking, and since websites consistently ignore DNT requests, it serves little purpose but to actually do the opposite and let companies fingerprint your device.
Although websites don't have to honor your request to stop being tracked, there's another feature that minimizes companies from tracking you across Safari and its WebKit versions.
Ever get tired of visiting one website and then getting ads for it on other websites? With Intelligent Tracking Prevention, a feature built-in to Safari, advertisers can only perform this "cross-site tracking" for 24 hours. Block cross-site tracking by going to "Settings." Tap on "Safari," then turn on "Prevent Cross-Site Tracking."
Although "Limit Ad Tracking" anonymizes your personal information, it's still collected in the form of tracking cookies. Yes, you can block cookies in general, but most websites need them to operate normally.
However, you can prevent tracking cookies pertaining to advertisers from being created in the first place with applications like Crystal, 1Blocker, and Firefox Focus. Some of these are merely content blockers for Safari, while others like Firefox Focus are both a content blocker and a web browser itself (that uses WebKit, of course).
This article was produced during Gadget Hacks' special coverage on smartphone privacy and security. Check out the whole Privacy and Security series.