Reducing your data trail on a Mac and phone

The earlier lessons described where data brokers get their material. This lesson is about the settings you already have, on a Mac and an iPhone, that reduce how much of it comes from you: app permissions, tracker blocking in the browser, and cutting down on the identifiers you hand out, such as your real email and phone number.

Control which apps can see what, on the Mac

Every Mac has a central place to review this. Apple’s own instructions: go to “Apple menu > System Settings, then click Privacy & Security in the sidebar.” From there, each category — Location Services, Contacts, Camera, Microphone, Photos, Bluetooth, Local Network and more — lists the apps that have requested access, and you can approve or remove each one individually. It is worth reviewing this list occasionally rather than only at install time: an app that legitimately needed your location once for a one-time feature does not need standing access to it forever.

On iPhone: App Tracking Transparency names the destination directly

On iPhone, iPad and Apple TV, Apple’s App Tracking Transparency feature is unusually specific about what it protects against. Apple defines “tracking” as when information that identifies you or your device, collected in one app, is linked with information collected elsewhere for advertising, “or when the information collected is shared with data brokers.” Go to Settings, then Privacy & Security, then Tracking, to see which apps have asked and to turn permission on or off per app; turning off “Allow Apps to Request to Track” in that same screen treats every future request as already declined. This is the one setting on the phone that is explicitly, officially, about data brokers rather than a general privacy label.

Block cross-site tracking in the browser

In Safari on the Mac, Apple’s instructions are to go to “Safari > Settings, then click Privacy” and select “Prevent cross-site tracking.” With that on, cookies and data from a third-party content provider are deleted unless you actually visit and interact with that provider as a first-party site — which is exactly the third-party tracking cookie behaviour described in the earlier lesson on how your data gets out. Safari also limits fingerprinting by presenting “a simplified version of your system configuration” to sites, and blocks social media “Like” or “Share” buttons from tracking you until you actually choose to use them. The same setting exists in Safari on iPhone. If you use a different browser, look for an equivalent option, usually named tracking prevention or cross-site tracking protection, and consider adding a dedicated tracker-blocking extension such as EFF’s Privacy Badger, which blocks third parties it observes tracking you across sites.

Stop handing out your real email and reduce what a phone number ties together

A large share of what ends up with data brokers starts with a form: a newsletter sign-up, an account creation, a warranty registration. Apple’s Hide My Email, part of iCloud+, lets you “generate unique, random email addresses…so you don’t have to share your real email address”, on iPhone, iPad, Mac or iCloud.com; mail sent to that address forwards to your real inbox, and you can delete an address later if it starts attracting spam or turns out to have been resold, without touching your main address at all. The same logic applies to phone numbers where you have a choice: a number given out for every sign-up, delivery or loyalty card is a stronger, more permanent link between accounts than an email alias, so it is worth being as selective about handing it out as you would be with your main email address, and using a masked address instead wherever a service accepts one.