These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.
Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.
This is a collection of web page captures from links added to, or changed on, Wikipedia pages. The idea is to bring a reliability to Wikipedia outlinks so that if the pages referenced by Wikipedia articles are changed, or go away, a reader can permanently find what was originally referred to.
books.google.com.au - Morgan discusses the origin of the emerald, its peculiar structure, and its strange allure. The story weaves across several continents and thousands of years. It is a tale of conquistadors, treachery, shipwrecks, and alchemy. Along the way, we meet scientists and kings and bear witness as the great emeralds...https://books.google.com.au/books/about/From_Satan_s_Crown_to_the_Holy_Grail.html?id=wb3ySfyMArUC&utm_source=gb-gplus-shareFrom Satan's Crown to the Holy Grail