Hilltop is a ranking method from Krishna Bharat and George Mihaila, developed at Compaq's Systems Research Center and published at WWW10 in 2001. It ranks pages by links from independent expert pages, meaning topic directories that link to many unaffiliated sources. Bharat later joined Google, but the Hilltop patent is held by HP's successors, not Google, and Google has never confirmed using Hilltop. The durable lesson is that links from independent, topical resource pages carry more meaning than links from related sites.
What is the Hilltop algorithm?
Hilltop is a ranking method for popular queries described by Krishna Bharat and George A. Mihaila in When Experts Agree: Using Non-Affiliated Experts to Rank Popular Topics, presented at WWW10 in Hong Kong in May 2001. The paper says the research was done at Compaq's Systems Research Center, where Bharat worked and Mihaila was a summer intern in 1999.
Its central idea is that the best pages on a popular topic are the ones that independent experts on that topic link to.
Our algorithm operates on a special index of "expert documents." These are a subset of the pages on the WWW identified as directories of links to non-affiliated sources on specific topics.
Krishna Bharat and George A. Mihaila, When Experts Agree: Using Non-Affiliated Experts to Rank Popular Topics, WWW10
How does Hilltop rank pages?
Hilltop works in two stages. First, it builds an index of expert pages: pages about a topic that link to many sources which are not affiliated with each other. The paper treats two hosts as affiliated if they share the first three octets of their IP address or the same rightmost non-generic part of the hostname, so a network of sites owned by one company cannot vouch for itself.
Second, at query time it finds the experts relevant to the query and ranks target pages by how many independent experts link to them, with extra weight when the query terms appear in the text that qualifies the link, such as the page title, a heading above it or the anchor text. When no pool of experts is available, the paper says Hilltop provides no results, so it is tuned for accuracy on popular topics rather than coverage.
Results are ranked based on the match between the query and relevant descriptive text for hyperlinks on expert pages pointing to a given result page.
Krishna Bharat and George A. Mihaila, When Experts Agree: Using Non-Affiliated Experts to Rank Popular Topics, WWW10
What evidence is there that Google uses Hilltop?
This is General theory. Google has never confirmed using Hilltop, and the patent does not belong to Google. The Google Patents record for US7346604, Method for ranking hypertext search results by analysis of hyperlinks from expert documents and keyword scope, filed on 15 October 1999 with Bharat and Mihaila as inventors, shows it assigned to Digital Equipment Corporation, then Compaq, Hewlett-Packard, Hewlett Packard Enterprise and, in 2021, Valtrus Innovations. Google does not appear in its assignment history.
The link to Google is Bharat himself: the WWW10 paper lists his current address as Google, and he went on to create Google News. Wikipedia's Hilltop article says Google acquired the algorithm for news results in February 2003, but that claim rests on dated third-party reporting and we could not verify it with Google or the patent record. Treat any claim that Hilltop runs in Google Search today as unproven.
What are the common myths about Hilltop?
- Myth: Google owns the Hilltop patent. The patent record shows it passed from DEC and Compaq to HP and then Valtrus Innovations.
- Myth: only directory links matter. The 2001 paper used directory-like expert pages because that is what the web offered then; the principle is independence and topicality, not directories.
What does Hilltop mean for sites?
The part worth acting on is independence. A link from a resource page that lists many unrelated organisations on your topic is a stronger vote than ten links from sites that share your ownership, hosting or network. That principle is consistent with Google's spam policies, which treat link schemes and cross-linking networks as link spam.
The falsifiable audit: group your referring domains by owner, IP range and registration details. If a large share trace back to the same owner, the same agency network or your own properties, those links would count as affiliated under Hilltop's logic, and look like a link scheme under Google's policies.
We define an expert page as a page that is about a certain topic and has links to many non-affiliated pages on that topic.
Krishna Bharat and George A. Mihaila, When Experts Agree: Using Non-Affiliated Experts to Rank Popular Topics, WWW10
Which Laurelin audit checks test for Hilltop-style issues?
The new check, Backlinks come mainly from affiliated sites, clusters referring domains by shared ownership and hosting signals. It measures a proxy for Hilltop's non-affiliation test, not a confirmed Google system.
Related checks:
- Inauthentic bought mentions or links: networks of affiliated sites are often bought placements.
- Toxic or spammy backlink profile: private blog networks usually show up here too.
- Expired domain or parasite abuse: expired domains are a common way to build affiliated link networks.
- Unnatural link velocity: networks often add links in bursts.
- Brand rarely co-mentioned with its topic: independent experts in a topic tend to mention the brands that matter in it.
What are the key dates for Hilltop algorithm?
Frequently asked questions about Hilltop algorithm
Does Google use the Hilltop algorithm?
Google has never confirmed it. The inventor Krishna Bharat joined Google, but the patent is held by HP's successors and there is no verified evidence of Hilltop in Google Search.
What is an expert page in Hilltop?
A page about a specific topic that links to many sources that are not affiliated with each other, such as a well curated resource list.
Who owns the Hilltop patent?
Google Patents lists US7346604 as originally assigned to Digital Equipment Corporation and now assigned to Valtrus Innovations, after passing through Compaq and Hewlett-Packard.