SEO Lesson 8 Keyword Optimizing Header Tags H1 – H6 on Each Webpage by Tidyrank
via YouTube

One of the concerns about algorithms is the way that certain information can be privileged over other information due to its position in search rankings, and the bias that can be introduced by only showing search engine users links to content that is similar to content they’ve previously looked at.  This video shows some of the mechanisms behind how that happens.