Visitor stitching is a form of identity resolution that works across platforms, devices, and browsers to associate activity to the same visitor. This article describes how visitor stitching works, how to use the visitor ID attribute effectively. and best practices.

In this article:


Identity Resolution

Identity resolution is the process of collecting and matching user identifiers across browsers and devices to create a unified view of a visitor's engagement with your brand. 

For example, when a new visitor interacts with your brand, on your website or app, Tealium Collect generates an anonymous ID and includes it in the data sent to AudienceStream. This results in a new visitor profile, a record in AudienceStream that stores visitor attributes. The same visitor might have several profiles in AudienceStream, one for each device or browser, and over time they accumulate more data.

Eventually, when the visitor validates their identity, Tealium Collect sends a user identifier to AudienceStream to indicate that it is a known visitor. The user identifier populates a visitor ID attribute in AudienceStream which triggers visitor stitching.


Identifying Anonymous Visitors

When AudienceStream processes events, the anonymous ID (tealium_visitor_id) is evaluated before any user identifiers or visitor ID attributes.

The following scenarios describe how the identifiers affect the visitor profiles in AudienceStream:

New Anonymous Visitor

If the anonymous ID does not match an existing profile, a new visitor profile is created.


Updated Anonymous Visitor

If the anonymous ID matches a visitor profile, the event enriches the existing profile.


Identified Visitor

If the event includes a user identifier that is configured to enrich a visitor ID attribute, and the visitor ID attribute is not populated already, the user identifier enriches the visitor ID attribute and the event enriches the existing profile.

Anonymous Visitor Matches Identified Visitor

If the event includes a user identifier that is configured to enrich a visitor ID attribute, and the user identifier matches the visitor ID attribute in an existing profile, the two profiles are stitched together.

Multiple Identifiers

If the event contains multiple user identifiers, the corresponding visitor ID attributes are evaluated as an OR condition in attribute ID order. This means that the visitor ID attribute that was created first will get evaluated first. In some edge cases this order of evaluation can affect how profiles are stitched, particularly when the profiles have no common anonymous IDs.

One exception is for file import data sources where the evaluation order is determined by the visitor ID mappings.

After visitor profiles have been stitched, they cannot be separated.

Visitor Stitching

Visitor stitching is a process in AudienceStream that facilitates inter-browser, cross-platform, and cross-device identity resolution. Visitor stitching relies on the anonymous ID, user identifiers, and visitor ID attributes to combine all user sessions into a single visitor profile in AudienceStream.

Visitor stitching goes beyond combining the data from two or more profiles into one. To create the most accurate unified profile possible, Tealium’s proprietary technology ‘replays’ the data from each of the stitched profiles, in order of occurrence, building the new profile based on the sequence of the visitor's journey. Stitching occurs in real-time and newly combined profiles can be immediately acted upon, thus making personalization, remarketing, and retargeting actions much more personalized and effective.

Visitor stitching can only be enabled by Tealium Support. Visit Support Desk to request that visitor stitching be enabled for your profile.


The following diagram shows how visitor stitching works when a user visits a website from three different devices. As each visitor session is identified to be the same user based on email address, a new visitor profile is created in AudienceStream to combine the previous known profiles. This is the visitor stitching process in action.


Important Notes

Here are some important guidelines to consider about visitor ID attributes and visitor stitching:

  • Uniqueness
    A visitor ID attribute must have at least 3 unique characters and be at least 6 characters long.
    Learn more about visitor ID attribute requirements.
  • Case Sensitive
    Visitor ID attribute values are case sensitive so, "" is different from "". If the attribute values contain these variations, use the lower-case enrichment to normalize them.
  • Multiple IDs
    Multiple visitor ID attributes are evaluated as an OR condition in order of attribute ID from lowest to highest (oldest to newest).
  • Robustness
    Only user identifiers that are guaranteed to match the visitor across devices should be used for visitor ID attributes.
  • Stitched Visitor Profile
    When multiple visitor profiles are stitched, the original profiles remain and a new visitor profile is created to store the stitched profiles.
  • Avoid Test Data
    Be careful not to capture default or test values in your user identifiers, such as, undefined, unknown, or not set.
  • Shared IDs
    Before stitching is enabled, determine how to handle shared IDs, such as those used at libraries or universities, so that multiple visitors are not stitched inadvertently.

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