29 August 2025

What is the Importance of Device ID in Mobile Advertising

Device ID is a unique and anonymous identifier assigned to a mobile device such as a smartphone or tablet. It plays a key role in in-app advertising: it enables a better understanding of user behavior and allows for more personalized interactions.

We explain the role of device ID in mobile advertising, the types of identifiers, and why this tool has gained importance as cookies lose relevance.

How device ID works

A device identifier, or device ID, is a unique anonymous number. Advertisers use it to set up targeted advertising.

In simple terms, when an app is launched for the first time, it requests the device ID. With user consent, it gets access to the identifier. From there, it can be used for ad targeting.

Device ID in mobile advertising helps find the right audience and segment it by interests to deliver precise ad messages.

Step-by-step process of using device ID in mobile advertising:

Requesting the ID. When a user installs an app, the app asks the operating system for access to the advertising identifier. If the user agrees, the app receives the unique anonymous code.
Transferring the ID. Once obtained, the app can share it via SDK with ad networks or analytics platforms. This allows advertisers to link clicks and app installs to specific identifiers and accurately measure campaign performance.
Targeting and ad delivery. Device ID helps group users by behavior, interests, or demographics (e.g., music fans, car buyers). These segments are then used for ad campaigns.
Analytics. When a user clicks an ad, installs an app, or takes actions inside it, the SDK logs these events by device ID, connecting them with ad distribution. This shows advertisers which campaigns or creatives drive results, while also preventing ad overload.

95% of Android apps collect at least one device identifier. 72% use device ID in mobile advertising to deliver personalized ads.

Device ID in mobile advertising: examples of usage

Retail app: shows discount ads only to users who already installed the app and made purchases.
Mobile game: retargets users who reached level 3 but didn’t purchase an in-game pack.
E-commerce: builds look-alike audiences based on current buyers’ device IDs.

Advantages over desktop

Using device ID in mobile advertising is one of mobile’s main advantages compared to desktop, where cookies are the main data source.

Benefits:

Stability & accuracy. Unlike cookies, device ID is tied to the device, not the browser. Data is not lost when clearing cache. Cookies are also blocked by browsers — Safari, Firefox, and Chrome are phasing out third-party cookies.
Cross-app analytics. Device ID enables tracking user behavior across different apps, not just a single website.
Better targeting. It allows for precise segmentation and reaching users most likely to convert.
Attribution. Device ID in mobile advertising links ad clicks to app installs or in-app conversions — critical for in-app marketing.

However, iOS (with ATT) and Android (with Privacy Sandbox) restrict access, so marketers must look for alternatives:

Contextual targeting (ads based on app context, e.g., fitness apps showing healthy food ads).
User interests (e.g., Google Ad Topics).
First-party data (information collected directly from users through owned channels).

Types of device ID

IDFA (Identifier for Advertisers): used on Apple devices. Access requires explicit user consent since iOS 14.5.
GAID (Google Advertising ID): used on Android. Users can opt out of personalized ads in settings.

How BYYD uses device ID

Anti-fraud system

BYYD has its own anti-fraud system based on device ID and its history in past auctions. It tracks geo-locations and device data tied to each ID to detect suspicious activity.

Benefits:

Prevents fake clicks and impressions
Ensures advertisers receive high-quality traffic
Improves attribution and ROI

Brand Lift studies

Device ID in mobile advertising is also used to measure brand campaigns. IDs allow researchers to form control and exposed groups of users for surveys.

For instance, during the promotion of REEDER BYYD conducted a Brand Lift study to find out how many people had heard about the campaign.

Device ID in the privacy era

Device-level data remains a valuable source for analytics and machine learning.

Still, obtaining user consent is critical. Apple’s ATT requires explicit opt-in on iOS, and similar frameworks are expanding.

Device ID in mobile advertising: key takeaways

How it works & types: Unique anonymous ID tied to smartphones/tablets. IDFA (Apple), GAID (Google).
Role: Enables precise targeting, retargeting, attribution, analytics, and Brand Lift studies.
Advantages over cookies: Stability, cross-app data, better targeting, reliable attribution.

Want to reach your target audience? In-app advertising powered by device ID in mobile advertising delivers accurate targeting and measurable campaign results.

Check out our case studies — and discover the power of strategic in-app advertising.