I understand the mapping process and the MCID/ ECID, and the execution of Customer Attributes in general, but still struggling to understand how CRM data can be attributed to anonymous web behavioral data? I presume the browser/searcher needs to authenticate on the website at some point to be tied to the offline CRM data? If not, how do I know if someone who bought 'Widget A' at the Widget Store offline, also visited Widgets.com prior to their purchase? How does that anonymous data tie in with the known data?
attributeCustomer AttributesECIDMCIDoffline data load
That's correct. If you want to tie a users offline CRM data to their online web data they would need to authenticate at least once. With that said, there may still be opportunities to use that data on a larger scale with something like look-a-like models or other options available via Experience Platform and Audience Manager (assuming you have access to those solutions).