In short: The advertising ID is a unique code your phone hands to apps so ad networks can recognize you across different programs and serve targeted ads. On Android it is the GAID (Google Advertising ID); on iPhone it is the IDFA. You can reset or fully delete it in settings in under a minute: on Android under Privacy → Ads, on iOS by turning off tracking under Privacy & Security → Tracking. Resetting removes the app-level advertising leash, but it does not hide your IP address — that is what a VPN is for. Maximum privacy comes from the pair: a reset advertising ID plus a VPN.
What the advertising ID actually is
The advertising ID is a unique string that your phone operating system gives to installed apps. On Android it is called the Google Advertising ID (GAID, sometimes AAID); on iPhone and iPad it is the IDFA (Identifier for Advertisers). The logic is simple: the cookies that link you across websites in a browser do not work inside mobile apps, so the ad industry invented a separate cross-app identifier. Any app with an ad module can read this code and pass it to an ad network.
Unlike a serial number or IMEI, the advertising ID is designed to be resettable: you can zero it out or delete it at any time, and the phone issues a new random string. But until you do, the identifier stays constant and serves as a convenient key that stitches your activity across different apps into a single profile. That is why it is called a leash — it follows you from app to app.
How the advertising ID tracks you
The string itself is harmless. The danger is what gets attached to it. Ad SDKs inside apps send your identifier to ad exchanges along with events: which app you opened, what you searched, which products you viewed, sometimes an approximate location. On the ad platforms, these events pile up and turn into an interest profile tied to one string.
- Cross-app stitching. A game, a banking app, a delivery service and a marketplace all see the same ID — so the ad network knows one person is behind all of it.
- Data brokers. Profiles tied to an advertising ID are bought and resold, merged with other datasets about users.
- De-anonymization. The identifier is considered anonymous, but the moment one app learns your phone number or email, it stops being anonymous.
- Retargeting. Ads follow you from app to app precisely because the identifier is shared across them.
We covered who else collects data from your phone, and how, in our guide on stopping phone tracking.
What an ad profile means in practice
Personalized ads may look like mere convenience. But the profile built around your advertising identifier reaches far beyond banners.
- Price discrimination. Knowing your interests and phone model, platforms can show different prices and offers to different people.
- Targeted deception. A detailed profile makes spear phishing and scam ads easier: the more that is known about you, the more convincing the bait.
- Data breaches. Ad and broker databases leak from time to time. When they do, the profile collected about you ends up exposed together with the identifier.
- Loss of control. You cannot see who bought your profile or how it is used next — the data takes on a life of its own.
Limiting the advertising ID is not paranoia but hygiene: you reduce the number of points where data about you accumulates. The same principle applies to removing your digital footprint overall.
Advertising ID, cookies and IP address: different leashes
The advertising ID is not the only signal used to recognize you. To understand what you are disabling and what remains, it helps to sort the identifiers out: each lives in a different place and is limited in a different way.
| Identifier | Where it lives | Who reads it | How to limit it |
|---|---|---|---|
| Advertising ID (GAID / IDFA) | In the phone OS settings | Apps and embedded ad SDKs | Reset or delete in settings, block tracking |
| Browser cookies | In the browser, on the device disk | Websites and web trackers | Clear cookies, blockers, private mode |
| Device fingerprint | Computed from device parameters | Websites and anti-fraud systems | Anti-fingerprint browsers, uniform settings |
| IP address | Assigned by the network and ISP | Any server you connect to | VPN — swaps your IP for a server address |
The advertising ID and the IP address live in different places and need different tools: one is closed in phone settings, the other on the network route. That is why resetting the identifier and using a VPN do not replace each other — they complement each other.
How to disable and reset the advertising ID on Android
On Android you can both reset the advertising ID (get a new random string) and delete it entirely — after which apps get back a string of zeros and lose the cross-app key.
- Open your phone Settings.
- Go to Privacy → Ads. On some builds the path differs: Settings → Google → Ads, or Settings → Google → All services → Ads.
- Choose Delete advertising ID to turn it off completely, or Reset advertising ID for a new random string.
- Confirm. After deletion, apps stop receiving a cross-app ID.
The option to delete the identifier entirely arrived in Android 12; on older versions only a reset is available. In the same section it is worth turning off ad personalization if the option is there.
How to limit the IDFA and tracking on iPhone
On iPhone the IDFA advertising identifier has been closed by default since iOS 14.5: apps must ask permission to track through the App Tracking Transparency mechanism. You can deny this globally.
- Open Settings → Privacy & Security → Tracking.
- Turn off Allow Apps to Request to Track. New apps then cannot even ask, and the IDFA is zeroed for them.
- Below, turn off tracking for any apps you previously allowed.
- Additionally, go to Settings → Privacy & Security → Apple Advertising and turn off Personalized Ads.
When tracking is denied, apps receive a string of zeros instead of the IDFA — the equivalent of a deleted identifier on Android. Setting up a new phone from scratch? That is a good moment to also close unnecessary app permissions.
What a reset does — and what it does not
Resetting or deleting the advertising ID breaks the history: the accumulated profile stops growing through the old ID, and retargeting loses you. But the step has clear limits.
- A reset does not erase data already collected about you — it only stops new events from being tied to the previous identifier.
- It does not affect browser tracking: there, cookies and the device fingerprint do the work, which is a separate story.
- It does not hide your IP address. From your IP a server sees an approximate location and your ISP, and ad and analytics systems use it as one more signal for stitching.
This is where a VPN comes in. A VPN does not change the advertising ID — that lives inside the phone — but it swaps your IP address for a VPN server address and encrypts your traffic, closing the network channel of tracking. Apps and sites see a de-identified network address, and your ISP or the Wi-Fi owner cannot see which services you connect to. We laid out honestly what a VPN does and does not cover in what a VPN protects against. Want to close the network leash? Start with the address: how to hide your IP address, and for ongoing protection use the LiMP VPN app for Android or iPhone.
Checklist: minimize ad tracking on your phone
- Delete (Android 12 and newer) or reset the advertising ID in settings.
- On iPhone, turn off Allow Apps to Request to Track and Personalized Ads.
- Review app permissions — especially location and background activity; remove what is unnecessary.
- Delete apps you do not use: every ad SDK is one more data collector.
- Install apps only from official stores and check what the installer asks for.
- Turn off ad personalization in your Google account and Apple ID.
- Turn on a VPN on public and other people networks to hide your IP and encrypt traffic.
- Repeat the identifier reset from time to time — until the next reset it becomes constant again.
Frequently asked questions
Does the advertising ID change when I factory reset the phone?
Yes, a full device reset creates a new identifier, just like a manual reset in settings. But you do not need to wipe the whole phone for that — a single option in the ads section is enough.
Does a VPN change my advertising ID?
No. The advertising ID lives inside the phone, and a VPN does not affect it. A VPN swaps your IP address and encrypts traffic — a different tracking channel. That is why they are used together: one closes the app layer, the other the network.
If I turned off tracking on iPhone, do I still need to do anything?
Turning off tracking closes the IDFA for apps, but browser cookies, the device fingerprint and your IP address remain. For the full picture it is worth closing those channels too.
Is it true that ads disappear without an advertising ID?
No, ads stay, but they become less personal: networks recognize you less well across apps. This is about privacy, not about blocking ads as such.
How often should I reset the identifier?
There is no strict rule. It makes sense every few weeks or after installing new apps. On Android it is simpler to delete the identifier once and forget about it.
Is the advertising ID visible on a computer?
No, it is a mobile app identifier. In a desktop browser, cookies and the device fingerprint do the tracking, while the signal shared across all your devices is the IP address, which a VPN hides.