[The new] Google Personalized Search uses My Search History data to refine your results based on your searching habits.Danny also quotes from a page at Google that apparently says:
Personalized Search is an improvement to Google search that orders your search results based on what you've searched for before. Learning from your history of searches and search results you've clicked on, Personalized Search brings certain results closer to the top when it's clear they're most relevant to you.It is excellent to see Google doing a real personalized search. Until now, tiny little Findory has been the only commercial search engine doing real web personalized search, changing search results based on your past behavior.
I suspect Google's personalized search is layered on top of their old personalized search which itself was layered on top of technology from Kaltix. So, if I were to guess, it probably works by building a high-level subject profile of your interests (e.g. sports, computers) from your history and biasing the search results toward those interests. That would be similar to the old personalized search where you had to explicitly specify that profile, but now the profile is generated implicitly using your search history.
In contrast, Findory's personalized web search is fine-grained, using information about individual pages you have viewed instead of high level subject interests. Our approach should allow the personalization to focus in on much more detailed interests and make more useful and relevant adjustments to the search results.
I think we will see the other search engines also move toward personalized web search. Many of the search engines -- Google, A9, Ask, Yahoo -- have a search history feature that helps you keep track of the searches you've made and search results you've seen. Personalized search is a natural extension of search history. As I said when Google Search History launched:
Keeping search and clickthrough history is a first step toward personalized search. The next big step is to use this data to reorder search results, making the results more relevant to your particular interests and needs.Danny Sullivan has long predicted this move toward personalized search:
This is where search is eventually headed. Everything will be personalized to make you feel like you have a more personal relationship with the Web site.And I have as well:
Personalized search is inevitable. With only one general relevance rank, it is increasingly difficult to improve search quality because not everyone agrees on how relevant a particular page is to a particular search. At some point, to get further improvements, relevance rank will have to be customized to each person's definition of relevance. When that happens, you have personalized search.See also quotes from Google Director Marissa Mayer and Google CEO Eric Schmidt on personalized search at Google.
See also my previous posts, "Why do personalized search?" and "A real personalized search from Google?".