Components of a search engine
- 1. Ms. T.Primya Assistant Professor Department of Computer Science and Engineering Dr. N. G. P. Institute of Technology Coimbatore
- 2. Search Engine refers to a huge database of internet resources such as web pages, newsgroups, programs, images etc. It helps to locate information on World Wide Web. User can search for any information by passing query in form of keywords or phrase. It then searches for relevant information in its database and return to the user.
- 3. The basic components of a search engine as listed below: Web Crawler Database Search Interfaces Ranking Algorithms
- 4. Web crawler It is also known as spider or bots. It is a software component that traverses the web to gather information. Variable features which can affect the search results Included Pages Excluded Pages Document Types Frequency of Crawling
- 5. Database All the information on the web is stored in database. It consists of huge web resources. Variable features which can affect the search results Size of the database Freshness of the database
- 6. Search Interfaces This component is an interface between user and the database. It helps the user to search through the database. Variable features which can affect the search results Operators Phrase Searching Truncation
- 7. The Ranking Algorithm How a search Engine ranks the results of the search .Most searches will retrieve thousands of results. Variable features which can affect the search results Location and frequency Link Analysis Clickthrough measurement
- 8. Search engines make use of Boolean expression AND, OR, NOT to restrict and widen the results of a search. Following are the steps that are performed by the search engine: The search engine looks for the keyword in the index for predefined database instead of going directly to the web to search for the keyword. It then uses software to search for the information in the database. This software component is known as web crawler. Once web crawler finds the pages, the search engine then shows the relevant web pages as a result. These retrieved web pages generally include title of page, size of text portion, first several sentences etc.
- 10. Indexing Process Indexing process comprises of the following three tasks: Text acquisition Text transformation Index creation Text Acquisition It identifies and stores documents for indexing. Text Transformation It transforms document into index terms or features. Index Creation It takes index terms created by text transformations and create data structures to support fast searching.
- 11. Query process comprises of the following three tasks: User interaction Ranking Evaluation User Interaction It supports creation and refinement of user query and displays the results. Ranking It uses query and indexes to create ranked list of documents. Evaluation It monitors and measures the effectiveness and efficiency. It is done offline.
- 12. Google Bing Ask Alexa AltaVist