Internet

How does a Web Search Engine works ?

Search Engine is the software program that helps users to find information stored on a personal computer, or a network of computers, such as the Internet. A user enters a keyword or a phrase. The search engine retrieves a list of Web order:

(a) Web crawling

(b) Indexing

(c) Search Algorithm

Web Crawling

The search engine works by matching the needed information from different websites and storing many web pages. These pages are then retrieved by a Web crawler (also known as a spider).

The contents of each page are then analyzed to check how it should be indexed. For example, words are extracted from the titles, and headings are shown.

Data collected on web pages are stored in an index database for use in later queries. The purpose of an index is to get information as quickly as possible. Some search engines, store all or part of the source page as well as information about the web pages.

Indexing

The indexing software collects the document as well as URLs from the agent. The software then extracts information from the documents and indexes it. Each search engine extracts and indexes different types of information.

When a user enters a query into a search engine by using keywords, the engine examines its index and provides a listing of best-matching web pages according to its criteria. The index is thus built from the information stored with the data and the method by which the information was indexed.

Search Algorithm

Search using Boolean operators allow you to combine words and phrases using the words AND,  OR and NOT to specify the search more accurately. When we perform the search by entering keywords, the search engine searches its database using a search algorithm. The Boolean operators AND, OR and NOT work as follows:

  1. AND- The pages found in the search must contain all the words joined the OR operator. For example, the search phrase wireless or communication will find pages that contain either and communication. Some search engines use the plus symbol ‘+’ instead of AND, for example, wireless + communication.
  2. OR- The pages found in the search must contain either of the words joined the OR operator. For example, the search phrase wireless or communication will find pages that contain either wireless or communication words.
  3. NOT- NOT command is used so that a particular search term should not be present in the listed results. For example, Buddhism NOT county finds documents on Buddhism but does not list documents on Buddhism county. Some search engine uses the minus sign (-) instead of NOT operator.
  4. NEAR- NEAR command is used to specify how close the terms should appear with each other — for example, heart NEAR chest.
  5. Capitalization—It should be essential for searching the proper names of the people, companies, or products. However, many words in English are both proper noun ande common nouns say for example Bill, bill, gates, Gates.
  6. Using Quotations to find specific phrases- Make use of quotation marks to find a particular phrase exactly as it appears in the search engine. For example, typing ‘Internet Explorer’ with quotation marks will not find pages that simply contain the terms Internet or Explorer in the web pages.

Meta Search Engine:

A metasearch engine is a searching tool. Through the Meta Search Engine tool, you can enter the other search engines, and the results will be accumulated into one list. The concept of Meta Search Engines has evolved since the search engine is an extensive platform from where it is difficult to search the different results for one search query. Therefore, the Meta Search Engines bring together the results from the various search engines.

The Metasearch Engine produced the best quality of results. The web produces many results, but the Meta Search Engine strained out the best from the entire search results. The list mentions InforGrid, which has a direct link to the famous sites and also the different websites which fall under the various categories.

The Dogpile helps in customizable search results. What it does is it directly sends the search to customizable directories, search engines, and popular search sites. Then they are categorized, and the search results are displayed as you want.

When to  use a metasearch engine

  • When you want to retrieve a relatively small number of relevant results
  • When your topic is doubtful
  • When you are not having luck finding what you want
  • When you want the convenience of searching a variety of different content sources from one search page

Examples of meta search engines

  • Browsys
  • Dogpile

Each one is a little different, though you will find that many use the same sources, for example, Google, Bing, Yahoo! And Ask. It makes sense that meta engines use the most famous, well-indexed, and comprehensive sources for their results. The difference is often in the search interface or in the presentation of the results.

Hence, Meta Search Engine becomes useful when searching becomes complicated with complicated topics, and searching has to be with accurate results.

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