Visitor ID attributes

Before you begin, familiarize yourself with the following:

• Using Attributes
• Using Enrichments
• About Visitor Stitching

A visitor ID attribute is configured in Customer Data Platform (CDP) to uniquely identify visitors. When you create a visitor ID attribute, you add an enrichment to set the value to a user identifier, which is an event attribute, such as email_address_hash or customer_id. For visitor stitching to work properly, you must choose a unique user identifier, create a rule to determine when to identify a visitor, and verify that the chosen attribute is unique for each visitor. For more information about selecting a user identifier, see Best practices for selecting user identifiers.

Visitor stitching is disabled by default. Contact your account manager to enable it.

Visitor ID attributes are available in the Visitor scope.

System requirements for visitor ID attributes

A visitor ID attribute must meet the following system requirements:

• Length: Values must be between 6 and 255 characters in length.
• Non-repeating: Values must contain at least 3 different characters. A 10-character identifier with only 2 different characters ( "a1a1a1a1a1" ) is invalid.
• Enrichment : Attributes with a data type of Number cannot be used to enrich a visitor ID attribute.
• Size: The maximum size of a visitor ID attribute is 2 KB.

UTF-8 character sets are supported.

The system automatically validates these requirements. You do not need these rule conditions in your visitor ID attribute configuration.

Best practices

A visitor ID attribute should follow these best practices:

• Uniqueness - Each visitor ID attribute value should be unique for each visitor.

  • Strong identifiers - Only use values that could be associated with a single visitor and are not likely to change, such as a hashed email address or customer ID.
  • Weak identifiers - Avoid values that cannot be guaranteed to be unique for each visitor or that have a high likelihood of changing over time, such as first and last name, username, or phone number.

• Case Sensitive - Values are case sensitive, so convert them to lower-case. For example, a single email address can be written with case variations such as FirstLast@example.com and firstlast@example.com, which would be treated as two different IDs in CDP.

• Verifying the Value - If you are using an email address, you may want to verify that the address contains the @ symbol. You may also want to check the string for other values such as, undefined, unknown, or not set or any text that would not be a valid value for a visitor ID attribute.

See Create a Visitor ID Attribute for a guide to creating the most accurate visitor ID attribute possible.

When to set a value for a visitor ID attribute

Set the value for a visitor ID attribute during a qualifying event, which is an event that occurs when a customer provides a reliable, unique means of identification, such as registering an account or completing a purchase.

A visitor ID attribute should not be a marketing activation ID (such as a gid). These third-party identifiers can be stored as visitor attribute for use in connectors, but are not recommended as visitor ID attributes.

Enrich a visitor ID attribute

Use an enrichment to store a user identifier for a visitor in a visitor ID attribute. For example, when a user registers or signs up, your system might generate an internal ID that is added to the data layer as customer_id. In this case, you would use an enrichment to set a visitor ID attribute to customer_id when the user_register event occurs.

After a visitor ID attribute is set, it cannot be updated.