Introduction

Google Search made the leap into the common culture's vernacular as a verb – “I'll google it” - because it works. You "google" it, often many times a day, as do millions of other people.
The corporate entity Google isn't thrilled that its name has become a verb, but it shows how powerful the search engine is, and how intricately it's become a part of everyday life.

When you type a query, you get precisely the information you want on the first page of the query results. If you don't, Google provides a multitude of other more specialized ways for you to search, via its vertical search engines, which include Blog Search, Book Search, Code Search, Patent Search, Scholar, and many more. However, many searchers aren't aware of Google's specialized search engines. Therefore Google has changed Google Search into Universal Search, which uses search personalization to provide a great user experience, and which now also includes the vertical search engines' indices.

In mid-2007, Google revamped its search engine to provide Universal Search. Now, instead of going to a specific search engine like Google Images, Google News, Google Video, or one of the other vertical search engines, Google serves up an all-in-one search. When you type a query, Google will present results across all its specialized search engines. Google's other vertical search engines, like Google Base and Froogle, are also now being folded into the primary search index.

Most people were never aware of Google's specialized search engines anyway before they were combined. From "Google 2.0: Google Universal Search": "You almost need a search engine for all our search engines," said Google's Marissa Mayer, vice president of search products … "We're so excited about taking all these different silos of information and making them all into one."

Universal Search: how does it work?

Google's Universal Search lets you search right across its vast index of databases, and across its specialized indexes simultaneously and automatically. Most users don’t know that they're searching many extended databases.

How does Google know what to present in its results when it’s searching such a massive amount of data? For example, when you type in a search like [green apple] and you receive your Universal Search results, they're usually just what you wanted at the time.

Universal Search – [green apple]

How does Google know? After all, [green apple] might mean: apple the fruit; apple the computer manufacturer; Gwynetth Paltrow’s daughter Apple; apple as an image etc.
Google knows, because it knows a lot about you.

Google has developed what the company calls "personalized search". It uses your own search history to guess what you want based on your past searches. Also, if you've ever signed up for a Google product like Gmail, AdSense, or the Google toolbar, Google also takes that information into  account when returning Universal Search results. This is transparent in use – most people aren't aware that Google keeps two years' of your search history, and other information, on its servers.

Web History – part of Google's Personalized Search

You can search your own Web History at any time, by creating an account with Google.