Competitors of Google include Baidu and in China; and in South Korea; Yandex in Russia; in the Czech Republic; Yahoo in Japan, Taiwan and the US, as well as Bing and Duck Duck Go.
When Google was a Stanford research project, it was nicknamed Back Rub because the technology checks backlinks to determine a site's importance.
Previous keyword-based methods of ranking search results, used by many search engines that were once more popular than Google, would rank pages by how often the search terms occurred in the page, or how strongly associated the search terms were within each resulting page.
The algorithm computes a recursive score for pages, based on the weighted sum of the Page Ranks of the pages linking to them.
Page Rank is thought to correlate well with human concepts of importance.
In addition to Page Rank, Google, over the years, has added many other secret criteria for determining the ranking of pages on result lists, reported to be over 250 different indicators, the specifics of which are kept secret to keep spammers at bay and help Google maintain an edge over its competitors globally. Schmidt reaffirmed this during a 2010 interview with the Wall Street Journal: "I actually think most people don't want Google to answer their questions, they want Google to tell them what they should be doing next." In February 2015 Google announced a major change to its mobile search algorithm which would favor mobile friendly over other websites.
The order of search on Google's search-results pages is based, in part, on a priority rank called a "Page Rank".
Google Search provides many different options for customized search, using Boolean operators such as: exclusion ("-xx"), alternatives ("xx OR yy OR zz"), and wildcards ("Winston * Churchill" returns "Winston Churchill", "Winston Spencer Churchill", etc.).
The same and other options can be specified in a different way on an Advanced Search page.
The main purpose of Google Search is to hunt for text in publicly accessible documents offered by web servers, as opposed to other data, such as images or data contained in databases.
It was originally developed by Larry Page and Sergey Brin in 1997.
These include synonyms, weather forecasts, time zones, stock quotes, maps, earthquake data, movie showtimes, airports, home listings, and sports scores.
There are special features for numbers, dates, and some specific forms, including ranges, Data about the frequency of use of search terms on Google can be openly inquired via Google Trends and have been shown to correlate with flu outbreaks and unemployment levels, and provide the information faster than traditional reporting methods and surveys.
As of mid-2016, Google’s search engine has begun to rely on these deep neural networks.