What is SEO and How Search Engine Works?

Search engine optimization (SEO) is the process of affecting the visibility of a website or a web page in a search engine's "natural" or un-paid ("organic") search results. In general, the earlier (or higher ranked on the search results page), and more frequently a site appears in the search results list, the more visitors it will receive from the search engine's users. SEO may target different kinds of search, including image search, local search, video search, academic search, news search and industry-specific vertical search engines.

How Search Engine Works

Search engines perform several activities in order to deliver search results.

Crawling: is the process of fetching all the web pages linked to a web site. This task is performed by a software, called a crawler or a spider (or Googlebot, as is the case with Google).Crawlers can validate hyperlinks and HTML code. They can also be used for web scraping

Indexing: is the process of creating index for all the fetched web pages and keeping them into a giant database from where it can later be retrieved. Essentially, the process of indexing is identifying the words and expressions that best describe the page and assigning the page to particular keywords.

Processing: When a search request comes, the search engine processes it . i.e. it compares the search string in the search request with the indexed pages in the database. 

Calculating Relevancy: Since it is likely that more than one pages contains the search string, so the search engine starts calculating the relevancy of each of the pages in its index to the search string.

Retrieving Results: The last step in search engines' activities is retrieving the best matched results. Basically, it is nothing more than simply displaying them in the browser.

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