Amit Singhal, Fellow in charge of the ranking team at Google discusses the “philosophies” behind Google ranking.
Google ranking is a collection of algorithms used to find the most relevant documents for a user query. We do this for hundreds of millions of queries a day, from a collection of billions and billions of pages. These algorithms are run for every query entered into most of Google's search services. While our web search is the most used Google search service and the most widely known, the same ranking algorithms are also used - with some modifications - for other Google search services, including Images, News, YouTube, Maps, Product Search, Book Search, and more.
The most common question I get asked about Google's ranking is “how do you do it?” Of course, there is a lot that goes into building a state-of-the-art ranking system like ours, and I will delve deeper into the technology behind it in a later post. Today, I would like to briefly share the philosophies behind Google ranking:
1) Best locally relevant results served globally.
2) Keep it simple.
3) No manual intervention.
He goes on to elaborate and points out to a policies for websites recommended by Google, and we do take action on sites that are in violation of our policies or for a small number of other reasons (e.g. legal requirements, child porn, viruses/malware, etc).