By default, customer records allow you to add standard customer data such as first names, last names, email addresses, and phone numbers. However, you may wish to store additional customer data. If you need to store additional information that is specific to your activity (e.g., a contract number or other customer references), you can create as many custom fields as you want. A custom field allows you to store extra customer data (such as contract number or customer references) in the customer record.
When you create a custom field, you specify whether the custom field will be associated with an identity or a case. When you associate the field with an identity, the field is visible and may be populated in the customer record. When you associate the field with a case, the information that populates this custom field will be received via API only and is not visible from the interface. You can use this type of custom field to integrate your CRM with the platform.
You can also create custom fields that are accessible only via API to retrieve data linked to the case. For example, you might want to do this when you need to integrate your CRM with the platform.