The AEM Recommendation generator is a content based recommendation engine which reads the metadata from pages and finds the similar pages to generate the recommendations, this tool leverages Apache Commons Math 3 library which is a lightweight library for performing statistical & mathematical calculations for generating the content based recommendations.
A recommendation engine can enhance the user experience by providing recommendations based on the data already available within the AEM system, these recommendation can range from a similar page recommendation on a blog to a product recommendation in case of an ecommerce website.
Follow this link for configuring the AEM Recommendation Generator.
Follow this link to go over the overall approach used for implementing AEM Recommendation Generator.