About: http://webisa.webdatacommons.org/245991643

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	While a proper answer to this question, especially the why and when part could take an entire book, I do think it is an excellent question that can be given at least some treatment here. +1 from me for the question.
http://www.w3.org/ns/prov#wasQuotedFrom	stackexchange.com