Properties that are used to describe customers on an ecommerce site. Most modern commerce platforms have their own, OOTB customer attributes (e.g. “First Name”, “Date of Birth”, “Phone Number”) and many offer merchants the ability to define their own custom attributes for customers. These custom attributes may be something that’s collected directly from the customer at the time they first register or these attributes can be populated from other sources like a CRM or ERP. These attributes can also be passed along to other systems like MAPs in order to help segment customers and provide them with more personalized messaging.