 Search engines are programs that search documents for specified keywords and returns a list of the documents where the keywords were found.  A search engine is really a general class of programs  “Search engine” is the popular term for an Information Retrieval (IR) system.

 Web Crawling  Indexing  Searching

 Web search engines work by sending out a spider to fetch as many documents as possible  Spider: an automated Web browser which follows every link on the site

 Data about web pages are stored in an index database for use in later queries  Index is to allow information to be found as quickly as possible.

 Document Processor  Query Processor  Search & Matching Function  Ranking Capability  Summarizing & Presenting Documents

 A meta search engine (also known as a multi-threaded engine) is a search tool that sends your query simultaneously to several search engines (SEs), Web directories (WDs) and sometimes to the so-called Invisible (Deep) Web, a collection of online information not indexed by traditional search engines.  A search engine that queries other search engines and then combines the results that are received from all.  After collecting the results, the meta search engine (MSE) will remove the duplicate links and, according to its algorithm, combine/rank the results into a single merged list.

 Search engine optimization (SEO) is the process of improving the visibility of a website or a webpage in a search engine’s "natural" or un- paid search result.  SEO is a technique which helps search engines find and rank your site higher than the millions of other sites in response to a search query  SEO is the activity of optimizing Web pages or whole sites in order to make them more search engine friendly, thus getting higher positions in search results.

 On Page SEO : This includes providing good content, good keywords selection. putting keywords on correct places, giving appropriate title to every page etc  Off Page SEO: T his includes link building, increasing link popularity by submitting in open directories, search engines, link exchange etc