A program (software system) or a web-based tool that is used to search the documents (information) by using the keywords on World Wide Web (www) is called search engine. World Wide Web is full of information. Today, there are thousands of search engines with different abilities and powerful features. Google, Yahoo, Bing, MSN and Ask.com are the popular search engines.
Google has become so powerful and well known search engine now a day. First text-based search engine was Veronica.
Search Engine Result Page (SERP):
When a searcher types a keyword query then the search engine displays a page called Search Engine Result Page (SERP). SERP is a listing of results in response to a keyword queries by a searcher. These results are of two types: first type is organic results and the second is sponsored results. Organic results are retrieved by the search engine’s algorithm and sponsored are advertisements. The results are ranked on a search engine according to the queries. For organic results, each result has the title of post or article, parmalink and short summary (description) on the SERP while in sponsored results, the advertiser makes decision & chooses what to display on SERP.
How Search Engine Works?
Internet search engines are special sites that are designed for help the people to find information stored on other websites. Crawling, indexing and ranking are the steps of a search engine.
Each search engine on the internet has its own spiders that go to different websites to discover the new URLs and different contents. Search engines have special and advance program for the crawling process. Web crawlers are the computer programs that scan and reading the websites. They also called spiders, bots and automatic indexers.
When a new web page is found, the spider reads the content and images. First Spiders go to the website and look at the robots.txt file (used for crawling restrictions by the webmasters). After crawling the URLs, they generate a copy of each page of the website and then pass it to index.
Index is the sets of database that contain millions of pages to display on search. Index is the big list of web pages and words. Indexed data is stored in encoded format to save the space. When a user types a query on search bar of a search engine, the search engine goes to its index library to fetch the required information for display. The search engine find millions of information in library but the algorithm of a search engine decides what information to display on SERP (Search Engine Result Page). Regularly updated websites with unique and genuine contents are given better position on SERP.
The last step of search engine is ranking. Each Search engine has its own ranking algorithm to rank the webpages of a website based on keywords. Search engines regularly update their algorithms.
List of Top 10 Search Engines in the World: