The New Your Times has recently published an article called “Google Keeps Tweaking Its Search Engine” about the Google search engine and the people working on it. A reporter from the magazine was allowed to spend a day with Amit Singhal, the mastermind behind the ranking algorithm and his collegues.
As Amit Singhal put it, the search has moved from “give me what I type” to “give me what I want”. For instance, someone typing “apple” is more likely to look for products from the Apple company than information about the fruit. Google uses hungreds of thousands of computers to index the web (basically indexing every single word from every page on the web, as well as compositions of words) and applies thousands of mathematical formulas to provide the best results.
Google uses a system of more than 200 types of information, called signals, to rank pages. Such signals could be words, links, images, history, data patterns extracted from queries. Then these signals are feed into formulas, called classifiers, that are doing the inference of useful information and provide the results. The results must offer a certain degree of diversity, because if one has more perspective the chances to find what is actually looked for are bigger.
Of course, the details about the search engine are the biggest kept secret at Google, but the article really worth reading.
