Web search engine …
A web search engine is a software system that is designed to search for information on the World Wide Web. The search results are generally presented in a line of results often referred to as search engine results pages (SERPs). The information may be a mix of web pages, images, and other types of files. Some search engines also mine data available in databases or open directories. Unlike web directories, which are maintained only by human editors, search engines also maintain real-timeinformation by running an algorithm on a web crawler.
Internet search engines themselves predate the debut of the Web in December 1990. The Who is user search dates back to 1982 and the Knowbot Information Service multi-network user search was first implemented in 1989. The first well documented search engine that searched content files, namely FTP files was Archie, which debuted on 10 September 1990.
In the summer of 1993, no search engine existed for the web, though numerous specialized catalogues were maintained by hand. Oscar Nierstrasz at the University of Geneva wrote a series of Perl scripts that periodically mirrored these pages and rewrote them into a standard format. This formed the basis for W3Catalog, the web’s first primitive search engine, released on September 2, 1993.
A search engine maintains the following processes in near real time:
- Web crawling
Indexing means associating words and other definable tokens found on web pages to their domain names and HTML-based fields. The associations are made in a public database, made available for web search queries. A query from a user can be a single word. The index helps find information relating to the query as quickly as possible.
Some of the techniques for indexing, and caching are trade secrets, whereas web crawling is a straightforward process of visiting all sites on a systematic basis.
Between visits by the spider, the cached version of page (some or all the content needed to render it) stored in the search engine working memory is quickly sent to an inquirer. If a visit is overdue, the search engine can just act as a web proxy instead. In this case the page may differ from the search terms indexed. The cached page holds the appearance of the version whose words were indexed, so a cached version of a page can be useful to the web site when the actual page has been lost, but this problem is also considered a mild form of linkrot.
Google is the world’s most popular search engine, with a market share of 80.52 percent as of March, 2017.
The world’s most popular search engines (with >1% market share) are:
East Asia and Russia
In some East Asian countries and Russia, Google is not the most popular search engine.
In Russia, Yandex commands a marketshare of 61.9 percent, compared to Google’s 28.3 percent. In China, Baidu is the most popular search engine.South Korea’s homegrown search portal, Naver, is used for 70 percent of online searches in the country. Yahoo! Japan and Yahoo! Taiwan are the most popular avenues for internet search in Japan and Taiwan, respectively.