Google first announced Search History in April 2005. By July 2005, Google Personalized Search was linked to My Search History and was monitoring what people selected from search results and refining their search results going forward based on their search habits.
Now with the most recent iteration of Web History, Personalized Search is working in the background even if you are not signed in to one of your Google accounts like Gmail.
In their official blog on December 4, 2009, Google said: "Previously, we only offered Personalized Search for signed-in users, and only when they had Web History enabled on their Google Accounts. What we're doing today is expanding Personalized Search so that we can provide it to signed-out users as well."
This is what Google says about Personalized Search:
+View and manage your web activity. You know that great web site you saw online and now can't find? From now on, you can. With Web History, you can view and search across the full text of the pages you've visited, including Google searches, web pages, images, videos and news stories. You can also manage your web activity and remove items from your web history at any time.
+Get the search results most relevant to you.Web History helps deliver more personalized search results based on the things you've searched for on Google and the sites you've visited. You might not notice a big impact on your search results early on, but they should steadily improve over time the more you use Web History.
+Follow interesting trends in your web activity. Which sites do you visit frequently? How many searches did you do between 10 a.m. and 2 p.m.? Web History can tell you about these and other interesting trends in your web activity.
Personalized Search then, changes your results by using data based on the types of sites you select from any and all of your searches. This may have an interesting effect on your Search Engine Optimization efforts as sites that a person typically searches for, or that Google determines they would be typically searching for, get a boost in rankings.
If you don't want this, next time you search in Google click on Web History link in your results page. It will have a link that you can click called "Disable customizations based on search activity" and that is the one you want.
There are many reasons you would want to turn Personalized Search off.
- You may not like the idea that Google is recording what you are doing online. This has always been an issue with Internet activity. Statistics on what we do on the Internet are now being tracked in the name of helping us as opposed to the old more obvious we want to know what to sell you approach.
- People switching computers will see different results unless they use all 3 the same way. What's the likelihood of that? Hope your IT guy doesn’t need to spend too much time on your computer and use Google at the same time. And you thought deleting history from your browser was enough…
- People will visit more and more of the same sites. It will become more and more difficult to find new things, original sources and small time publishers. I want to come up with the brilliant search query, not have Google tell me what I meant based on my prior history. I'm human and reserve the right to change my mind.
- Trying to ever get closer to human intelligence, results get weaker. I may be searching for schools for my children but where to repair my car next mixed in with my wife using my computer to shop online or plan our next vacation. Track that!
- My Internet Explorer keeps track of my history as does Firefox just fine so I don’t need a Google database somewhere in Internet land to keep a copy of my data.
- It seems obvious that we use search engines when we don't know what we are looking for. So why would I want my past search history to limit some new and unique (to me) question I need answered? How about this approach: let me search for what I want.
I'll be clicking on "Disable customizations based on search activity" now...