I have a number of sites/blog and also ecommerce sites. All on different domains
I wanted to see if there is a way to see a unique visitor irrespective of website. So the unique identifier issues from first visit is tracked across the ecosystem of sites and web properties.
Is there a way to track the same visitor across websites?
And then as a user ID once he/she gives their email via form or as a customer.
Then result is information is about an individual person then websites etc.
Any help would be greatly appreciated.