What is the A3 cookie?
The A3 cookie is set by Yahoo to assign a unique identifier for tracking user behavior across websites to display personalized advertisements and measure ad performance.
Table of Contents
About A3
| Vendor | Yahoo |
|---|---|
| Cookie Domain | atwola.com,yahoo.com |
| Category Category The functional category of the technology, such as Web Analytics or Social Media. Learn more | Web Analytics |
| Consent Category Consent Category The consent category this cookie most commonly falls under across sites we scan, normalized into four standard categories. Learn more | Targeting & Advertising |
| Prevalence | Very Common |
| Popularity Popularity Popularity is calculated from our dataset of 4.5B+ cookies analyzed across hundreds of millions of web pages. Learn more | Found on 18.6% of scanned pages |
| Expiration Type | Timestamp |
| Expiration Duration | 30 days |
| Party Type Party Type Whether the cookie is first-party or third-party. Learn more | 3rd-Party |
| Risk Level Risk Level Rates how sensitive the data stored by this cookie is (High, Medium, or Low) based on data classification and distribution. Learn more | High |
| Vendor Privacy Policy | https://legal.yahoo.com/us/en/yahoo/privacy/index.html |
| Vendor Website | https://www.yahooinc.com/ |
What is the purpose of A3?
The A3 cookie is a third-party tracking identifier set by Yahoo's advertising and analytics technologies (such as Yahoo Analytics and the Yahoo Advertising / Yahoo DSP ad-exchange and sync endpoints observed at ups.analytics.yahoo.com, sp.analytics.yahoo.com, and ybp.yahoo.com). According to Yahoo's own Cookie Policy, the A3 cookie 'stores a unique identifier which we use to display and measure advertising.'
This pseudonymous user ID enables Yahoo to recognise a browser/device across independent domains and to build content and advertising interest profiles. It is used to deliver and personalise programmatic ads, measure ad campaign performance and conversions, enforce frequency capping, and support fraud detection across Yahoo's advertising ecosystem.
What are the Privacy Risks of A3?
Risk Level: High
The A3 cookie functions as a persistent third-party advertising identifier that tracks users across multiple websites to build behavioral and advertising interest profiles. Since it stores a unique user identifier that Yahoo matches against its advertising partners' identifiers for cross-site targeting, ad measurement, and programmatic bidding, it poses a high privacy risk to end users.
How to Remove A3 from a Website
To remove this cookie, website administrators must identify and remove the Yahoo Analytics or Yahoo advertising/tracking tags (for example the sp.analytics.yahoo.com and ups.analytics.yahoo.com pixels, or Yahoo DSP retargeting tags) from the site's source code or tag management system. If the Yahoo tags must remain on the site for other functionality, administrators should adjust the tag configuration or contact their Yahoo representative to disable cross-site retargeting and personalized advertising features, which may prevent the advertising cookie from being set. If the cookie cannot be disabled independently of the Yahoo advertising service, the tag must be removed entirely to stop it from being set.