- Identity Service Help
- Overview
- Implementation
- Implementation methods
- Implementation guides
- Implement with Experience Platform tags
- Implement for Analytics
- Implement for Target
- Implement for Analytics and Audience Manager
- Implement for Analytics, Audience Manager, and Target
- Using the ID Service with A4T and a Server-side Implementation of Target
- Direct Integration with the ID Service
- Direct Integration Use Cases
- Test and verify the ID Service
- Opt-in Service
- ID Service API
- ID Service API Overview
- Configuration
- Configurations overview
- audienceManagerServer and audienceManagerServerSecure
- cookieDomain
- cookieLifetime
- disableIdSyncs
- disableThirdPartyCalls
- disableThirdPartyCookies
- idSyncAttachIframeOnWindowLoad
- idSyncContainerID
- idSyncSSLUseAkamai
- loadTimeout
- overwriteCrossDomainMCIDAndAID
- resetBeforeVersion
- sdidParamExpiry
- Secure and SameSite configurations
- secureCookie
- useCORSOnly
- whitelistParentDomain and whitelistIframeDomains
- Methods
- Methods
- appendSupplementalDataIDTo
- appendVisitorIDsTo (Cross-Domain Tracking)
- callTimeOut Methods
- ID Synchronization by URL or Data Source
- getInstance
- getAnalyticsVisitorID
- getCustomerIDs
- setCustomerIDs
- getMarketingCloudVisitorID
- getLocationHint
- getVisitorValues
- isClientSideMarketingCloudVisitorID
- resetState
- Reference
- Reference Overview
- Analytics Reference
- Analytics Reference Overview
- CNAME Implementation Overview
- Setting Analytics and Experience Cloud IDs
- Order of Operations for Analytics IDs
- ID Service Migration Decision Points
- ID Service Migration Scenarios
- Analytics and Identity Requests
- Server-side Implementation Mixed with JavaScript
- The ID Service Grace Period
- Google Chrome SameSite labelling changes
- Content Security Policies and the ID Service
- COPPA Support in the ID Service
- CORS Support in the ID Service
- Customer IDs and Authentication States
- ECID library methods in a Safari ITP world
- Identifying Unique Visitors
- Get Region and User IDs From the AMCV Cookie or the ID Service
- Requirements for the ID Service
- Video Heartbeat and the ID Service
- Data Workbench and the ID Service
- SHA256 Hashing Support for setCustomerIDs
- FAQs
- Release notes for ID Service
Identifying Unique Visitors
The method for identifying unique visitors among multiple contexts includes a prioritized sequence to ensure accuracy in this determination. The following table shows this prioritized sequence:
| Order used | Query parameter (collection method) | post_visid_type column value | Present when |
|---|---|---|---|
| 1 | vid s.visitorID | 0 | s.visitorID is set. |
| 2 | aid s_vi cookie | 3 | Visitor had an existing s_vi cookie before you deployed the Visitor ID service, or you have a Visitor ID grace period configured. |
| 3 | mid AMCV_ cookie set by Identity Service | 5 | Visitor’s browser accepts cookies (first-party), and the Identity Service is deployed. |
| 4 | fid fallback cookie on H.25.3 or newer, or AppMeasurement for JavaScript | 4 | Visitor’s browser accepts cookies (first-party). |
| 5 | HTTP Mobile Subscriber header | 2 | Device is recognized as a mobile device. |
| 6 | IP Address, User Agent, Gateway IP Address | 1 | Visitor’s browser does not accept cookies. |
For information on how unique visitors are reported, see Unique Visitors in Analytics.
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