document: Genealogical trees on the web : a search engine user perspective This paper presents an extensive study about the evolution of textual content on the Web , which shows how some new pages are created from scratch while others are created using already existing content . We show that a significant fraction of the Web is a byproduct of the latter case . We introduce the concept of Web genealogical tree , in which every page in a Web snapshot is classified into a component . We study in detail these components , characterizing the copies and identifying the relation between a source of content and a search engine , by comparing page relevance measures , documents returned by real queries performed in the past , and click-through data . We observe that sources of copies are more frequently returned by queries and more clicked than other documents .
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