Hilltop was a search engine ranking algorithm used by Google during its early days, which primarily looked at a link structure of web pages to determine how far a page is recognised and relevant. Hilltop was not like the others that used keyword matching alone to find so-called “expert” pages on a certain topic: it studied the links pointing to them. The logic was that the pages had a very high likelihood of being authoritative themselves if many other pages had linked to them. Hilltop looked primarily at the “neighbourhood” of a page by analysing linking in and out from it, in addition to links pointing