Personalization Builder
The Personalization Builder provided by the Marketing Cloud is powered by Einstein and tracks customer interactions, such as email click, white paper download, purchase from sites, and other behaviors. There are predefined algorithms that can be configured in the email or Web Studio and which help us score the customer engagement.
The various algorithms available for predictive emails are documented in the official documentation (http://help.marketingcloud.com/en/documentation/personalization_builder/predictive_email/predictive_email_algorithms_defined).
With Email Studio and Personalization Builder, marketers can configure emails that can send recommended content to customers based on the rules defined in the Builder. Similarly, with Web Studio, marketers can deliver the next best personalized content to each website visitor.
In short, the AI baked into marketing will help marketers deliver the right content at the right time to reengage customers.