About visitor stitching

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.

Identifying your visitors is a critical step in making full use of Tealium AudienceStream CDP. When certain qualifying visitor events occur, such as a user registering or completing a purchase, there is an opportunity to uniquely identify that visitor using an event attribute such as email_address_hash or customer_id. When one of these identifying attributes is provided in the data layer across multiple sessions, AudienceStream can combine the visitor attributes from those sessions into one master visitor profile using a process called visitor stitching.

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

The Tealium identity resolution process uses several types of attributes, as follows:

  • Anonymous Identifier – an anonymous, unique value generated by Tealium Collect for each visit to a site or each use of an app.
  • User indentifier – an identifier, such as an email address, that uniquely identifies a user across devices, platforms, and browsers.
  • Visitor ID attribute – an attribute that is used in visitor stitching to identify users across sessions and devices. A visitor ID attribute gets its value from a User ID and is used to combine combine visitor profiles that have the same visitor ID attribute value into a single profile. Selecting the visitor ID attributes you will use for visitor stitching is an important part of AudienceStream configuration. For more information, see Visitor ID Attributes.

For more information, see Anonymous IDs, User IDs, and Visitor ID Attributes.

How identity resolution works

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.

When a visitor validates their identity, by providing a user identifier such as an email address, Tealium Collect sends this 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.


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.

For more information, see Visitor Stitching Example.

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

How AudienceStream evaluates identifiers

When AudienceStream processes events, the anonymous ID (tealium_visitor_id) is evaluated before any user identifiers or visitor ID attributes. The only exception to this order of evaluation is that for events from file import data sources, the evaluation order is determined by the visitor ID mappings.

The following scenarios describe how anonymous IDs and user 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. UserIDToKnownUser.png

  • 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 is evaluated first. In some edge cases, the order of evaluation can affect how profiles are stitched, particularly when the profiles have no common anonymous IDs.

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This page was last updated: January 7, 2023