05 Jun Internet Search Engine
Internet Search Engine
An Internet 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 time information by running an algorithm on a web crawler.
Internet content that is not capable of being searched by a web search engine is generally described as the deep web. A website that maintains an index and short summaries of billions of pages on the Web, Google being the world’s largest. Most search engine sites are free and paid for by ads. Yahoo was the first search engine to gain worldwide attention, and it initially indexed most of its content manually, creating a hierarchical directory that was put together by human observation. It was known then as a “directory” rather than a “search engine.” However, as Web content grew exponentially, it became impossible to index everything manually.
most indexing is done automatically by Web “spiders,” which are programs that “crawl” the Web around the clock looking for all the pages they can find. By following the links from one page to another, they scour billions of pages and summarize them in massive databases, which is what you query when you do a search.
“Metasearch” engines search other search engines and bring you results as if you went to each of them independently.
The Deep Web
An enormous amount of content that websites offer resides in databases that are not exposed to the search engines like ordinary HTML pages with links to each other. This “deep Web,” which is thousands of times larger than the public Web is accessible from the site itself and may require membership or a paid subscription.
Many search engine sites evolved into a portal. Instead of offering content only from other websites, they have their own content and features such as free email, chat rooms and shopping.
Search Engine Sites
Following are popular sites for searching any topic. If you do not find what you want at one site, try another, even if you use a metasearch engine. Spiders do not always find the same information at the same time.