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.The first search engine ever developed is considered Archie, which was used to search for FTP files and the first text-based search engine is considered Veronica. Today, the most popular and well known search engine is Google.
Because large search engines contain millions and sometimes billions of pages, many search engines not only just search the pages but also display the results depending upon their importance. This importance is commonly determined by using various algorithms.
On the Internet, a search engine is a coordinated set of programs that includes:
The search engine then analyzes the contents of each page to determine how it should be indexed (for example, words can be extracted from the titles, page content, headings, or special fields called meta tags). Data about web pages are stored in an index database for use in later 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 search engines, such as Google, store all or part of the source page (referred to as a cache) as well as information about the web pages, whereas others, such as AltaVista, store every word of every page they find.This cached page always holds the actual search text since it is the one that was actually indexed, so it can be very useful when the content of the current page has been updated and the search terms are no longer in it. This problem might be considered a mild form of linkrot, and Google's handling of it increases usability by satisfying user expectations that the search terms will be on the returned webpage. This satisfies the principle of least astonishment, since the user normally expects that the search terms will be on the returned pages. Increased search relevance makes these cached pages very useful as they may contain data that may no longer be available elsewhere.
When a user enters a query into a search engine (typically by using keywords), the engine examines its index and provides a listing of best-matching web pages according to its criteria, usually with a short summary containing the document's title and sometimes parts of the text. The index is built from the information stored with the data and the method by which the information is indexed. From 2007 the Google.com search engine has allowed one to search by date by clicking "Show search tools" in the leftmost column of the initial search results page, and then selecting the desired date range. Most search engines support the use of the boolean operators AND, OR and NOT to further specify the search query. Boolean operators are for literal searches that allow the user to refine and extend the terms of the search. The engine looks for the words or phrases exactly as entered. Some search engines provide an advanced feature called proximity search, which allows users to define the distance between keywords. As well, natural language queries allow the user to type a question in the same form one would ask it to a human. A site like this would be ask.com.
Using Search Engine
Because large search engines contain millions and sometimes billions of pages, many search engines not only just search the pages but also display the results depending upon their importance. This importance is commonly determined by using various algorithms.
On the Internet, a search engine is a coordinated set of programs that includes:
- A spider (also called a "crawler" or a "bot") that goes to every page or representative pages on every Web site that wants to be searchable and reads it, using hypertext links on each page to discover and read a site's other pages
- A program that creates a huge index (sometimes called a "catalog") from the pages that have been read
- A program that receives your search request, compares it to the entries in the index, and returns results to you.
Once a page has been crawled the data contained within the page is processed, often this involves stripping out stop words, grabbing the location of each of the words in the page, the frequency they occur, links to other pages, images, etc. This data is used to rank the page and is the primary method a search engine uses to determine if a page should be shown and in what order.
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-time information by running an algorithm on a web crawler.
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How Web Search Engine Work
A search engine operates in the following order:
- Web crawling
- Indexing
- Searching
Web search engines work by storing information about many web pages, which they retrieve from the HTML markup of the pages. These pages are retrieved by a Web crawler (sometimes also known as a spider) — an automated Web crawler which follows every link on the site. The site owner can exclude specific pages by using robots.txt.
When a user enters a query into a search engine (typically by using keywords), the engine examines its index and provides a listing of best-matching web pages according to its criteria, usually with a short summary containing the document's title and sometimes parts of the text. The index is built from the information stored with the data and the method by which the information is indexed. From 2007 the Google.com search engine has allowed one to search by date by clicking "Show search tools" in the leftmost column of the initial search results page, and then selecting the desired date range. Most search engines support the use of the boolean operators AND, OR and NOT to further specify the search query. Boolean operators are for literal searches that allow the user to refine and extend the terms of the search. The engine looks for the words or phrases exactly as entered. Some search engines provide an advanced feature called proximity search, which allows users to define the distance between keywords. As well, natural language queries allow the user to type a question in the same form one would ask it to a human. A site like this would be ask.com.
The usefulness of a search engine depends on the relevance of the result set it gives back. While there may be millions of web pages that include a particular word or phrase, some pages may be more relevant, popular, or authoritative than others. Most search engines employ methods to rank the results to provide the "best" results first. How a search engine decides which pages are the best matches, and what order the results should be shown in, varies widely from one engine to another. The methods also change over time as Internet usage changes and new techniques evolve. There are two main types of search engine that have evolved: one is a system of predefined and hierarchically ordered keywords that humans have programmed extensively. The other is a system that generates an "inverted index" by analyzing texts it locates. This first form relies much more heavily on the computer itself to do the bulk of the work.
Most Web search engines are commercial ventures supported by advertising revenue and thus some of them allow advertisers to have their listings ranked higher in search results for a fee. Search engines that do not accept money for their search results make money by running search related ads alongside the regular search engine results. The search engines make money every time someone clicks on one of these ads.
Google search engines and other major search engines like Bing and Yahoo use large, numerous computers in order to search through the large quantities of data across the web.
Web search engines catalog the world wide web by using a spider, or web crawler. These web-crawling robots were created for indexing content; they scan and assess the content on site pages and information archives across the web.
Algorithms And Determining The Best Search Engines
Different internet search engines use different algorithms for determining which web pages are the most relevant for a particular search engine keyword, and which web pages should appear at the top of the search engine results page.
Relevancy is the key for online search engines – users naturally prefer a search engine that will give them the best and most relevant results.
Search engines are often quite guarded with their search algorithms, since their unique algorithm is trying to generate the most relevant results. The best search engines, and often the most popular search engines as a result, are the ones that are the most relevant.
Search Engine History
Search engine history all started in 1990 with Archie, an FTP site hosting an index of downloadable directory listings. Search engines continued to be primitive directory listings, until search engines developed to crawling and indexing websites, eventually creating algorithms to optimize relevancy.
Yahoo started off as just a list of favorite websites, eventually growing large enough to become a searchable index directory. They actually had their search services outsourced until 2002, when they started to really work on their search engine.
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There is a plenty of material available on net. To take an effective on the web, you need to select the search site and compose the criteria carefully.
- Visit a Search Engine. One of the important search engine is Google. To visit this site type https://www.google.com in the address bar and press enter key.
- Conduct the search. To conduct search on Google, type the text you wish to search for in the search for : text box For example : Type 'microinfoweb'.
- Click the Google Search button to begin the search.
- View the search result. search engine will show you the best matched pages. You can click on Next > Hyperlink at the bottom of the page, to see more results.
- You can click on hyperlink to see the web page. Some Search Engine are-
The web also provided facility to download programs and files easily. Just right click on the Download Link. Chose Save Target As option and Click on Save button after specifying the file name.
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