Collection, Use, and Linking of Technical Identifiers

Yahoo uses different technical identifiers to make its consumer services available on most platforms, browsers, and devices. Yahoo also uses these technical identifiers to provide our digital advertising services on our properties and for our business partners.

As detailed in our Cookie Policy, these technical identifiers include:

  • Browser cookie identifiers (sometimes referred to as “cookie IDs”) and browser local storage identifiers
  • Mobile device identifiers, such as the Android advertising ID or the Apple Identifier for Advertising (IDFA)
  • Platform or operating system-based identifiers, such as those offered on smart or connected TVs or media streaming devices
  • Partner-supplied technical identifiers
  • Encrypted or one-way cryptographic hashes of personal information such as email addresses, phone numbers, account identifiers, derivatives, or escalated versions of these identifiers
  • Household-based identifiers
  • IP addresses
  • Probabilistic (non-unique) identifiers
  • Identifiers generated from the combination of various device, browser, or operating system attributes, such as the operating system or browser version
  • “Cohort”, audience, or group identifiers, such as “sports enthusiasts”

The storage, generation, and collection methods of these identifiers may also vary, depending on the context. For instance, some browsers and devices offer limited technical identifier support and/or limited cookie support, so non-cookie-based identifiers may be used in these cases. Examples of these devices include:

  • Smart or connected TVs, over-the-top (OTT) streaming devices (such as a Roku device), and similar interactive media players
  • Digital-out-of-home (DOOH) billboards and similar media devices
  • Browsers enabled with intelligent tracking prevention (ITP), privacy sandbox, or similar cookie-blocking technology
  • Certain apps, mobile devices, or installed software, where permitted and applicable
  • Certain internet-of-things (IoT) devices

The collection methods for technical identifiers and associated data depend on the context, as described here. When using the Internet in a browser (for example, Chrome), our consumer services and digital advertising services may use standard cookies, Javascript code, libraries, and/or dynamic HTML tags, web beacons, and similar technologies. In mobile apps, our consumer services and digital advertising services may use mobile software development kits (SDKs), local or remote application programming interfaces (APIs), and similar client or server-side code. In other cases, we may exchange data and files (such as log files) with our partners in “offline” contexts using secure server-to-server transfer methods, APIs, cloud services, mutual agents or technology service providers, or other industry-standard methods.

Technical identifiers may be used to identify a user across multiple devices, often referred to as “cross-device-linking” or “cross-device identifier resolution”. As a result, technical identifiers that are presumed to belong to a particular user, device, or household can be linked to one another, and the associated technical identifier may be used to reference data, personalise advertisements, or tailor experiences. This process may be implemented and used by us or in coordination with our advertising partners as part of our digital advertising services. Note that these techniques are not used for authentication or to secure your account in any way.

These technical identifiers are linked through common elements such as shared IP addresses, shared use of a device or a mobile app, account logins across multiple devices, and pre-matched or linked data provided by our third party partners. It is important to note that Yahoo typically uses the same technical identifiers whether you are using our consumer services, such as Yahoo Finance, or interacting with our digital advertising services, such as receiving a personalized advertisement on a partner’s website or app. This means your data and activity are generally linked and correlated across first and third party contexts and will be used to enhance your experience wherever you use our consumer services or interact with our digital advertising services.

In particular, some of our consumer services and digital advertising services make use of technical identifiers generated from one-way cryptographic hashes (defined below) of personal information collected from multiple sources, including:

  • Your Yahoo registered email account and associated contact information
  • Account recovery information you have provided to Yahoo to secure your account, including alternate email accounts and phone numbers
  • Information purchased from or provided by our business partners and data providers
  • Information obtained from operating our digital advertising services, including information supplied by advertisers and publisher partners
  • Publicly available information

Cryptographic Hash: A hash or cryptographic hash is an algorithm that irreversibly transforms a given piece of data into a new pseudonymous value. For example, a hashed email address can be used to correlate records and data belonging to the owner of the email address without the system ever knowing (or needing) the actual email address.

These hashed technical identifiers are used in our consumer services and our digital advertising services in the following ways: 

  • Personalised advertising, including programmatic advertising and real-time-bidding (RTB)
  • Audience-matched advertising, in cases where these hashed technical identifiers can be shared and/or matched in a secure, pseudonymous manner with our business partners, publishers, advertisers, and technology service providers
  • Audience measurement and market research (often performed by Comscore)
  • Advertising measurement, attribution, and conversion tracking
  • Advertising effectiveness studies and related financial reporting
  • Yahoo analytics 
  • Service improvement and development
  • Audience insights
  • Securing our services, anti-abuse (particularly in our public forums and comments sections), and anti-fraud efforts

Note that Yahoo may share these pseudonymous technical identifiers with our third party business partners and technology service providers in order to provide functionality to users of our services, including personalised advertising and audience-matched advertising services, analytics, audience research and measurement, and content personalization. Where such information is shared, partners are contractually required to respect all applicable data privacy laws and are prohibited from re-identifying any pseudonymous information. 

Note that our partners often also utilize their own proprietary technical identifiers and collection methods (which are generally similar to those used by Yahoo and other industry-standard practices) to perform all of the above services and related functionality. For more information regarding our partners’ collection and use of data, see Partners.

Technical Identifiers and Your Privacy Choices

You have privacy choices in how technical identifiers are used and shared. See the privacy choices section for more information about how to manage your privacy choices.

Please note the following regarding our use of technical identifiers and your privacy choices:

  • Platform Specific Privacy Choices: Some of the devices noted above, such as smart or connected TVs, may offer platform-specific privacy choices. Where such choices are applicable, available, and relevant to our digital advertising service being offered, Yahoo will support these choices. Where such choices are not supported by the platform or our digital advertising service, Yahoo will still respect your choices when effectuated via the Yahoo Privacy Dashboard.
  • Clearing Browser Cookies or History: Your information can be collected and indexed by technical identifiers that are generated through non-cookie-based methods. As a result, clearing browser cookies and/or browser history may not be an effective means of managing your privacy when using our consumer services or our digital advertising services. Use the Yahoo Privacy Dashboard to manage your privacy choices for best results.
  • Using Cookie Blockers: Many cookie-blocking browsers, ad blocking add-ons, and privacy-related extensions may interfere or block Yahoo’s ability to set and/or honor your privacy choices. This is because these technologies often block cookies and signals that Yahoo relies on to maintain or interpret user privacy settings. These components may also affect your ability to manage privacy choices offered by our third party business partners.