Hilltop algorithm

The Hilltop algorithm is used to find documents relevant to a particular keyword topic in news search. It was created by Krishna Bharat while he was at the Compaq Systems Research Center, together with George A. Mihaila of the University of Toronto, and Google acquired it for its news results in February 2003. The algorithm works on a special index of expert documents, which are pages about a specific topic that link to many non-affiliated pages on that topic. The original version relied on independent directories with categorized links to sites. Results are ranked by how well the query matches the descriptive text of hyperlinks on expert pages that point to a given result page. A website that has backlinks from many of the best expert pages is an authority and is ranked well, so the method rests on the relationship between experts, which link out to many relevant documents, and authorities, which receive links from those experts.