Brief explanation on how Search Engine works

As more people prefers to search for information on the internet, the internet search engines have become an important part to business marketing. There are various search engines available, like Google, Yahoo, MSN, etc. The most popular one of course is Google, so this article would focus mainly on the Google search engine.


What happens when a user do an organic search:
• The Search Engine first analyze the words the searcher typed in and pick the pages that match those words
• It will then ranks the matches.
• Finally it displays the search results.


How Search Engines Find web pages for the organic indexes
• Search Engine Spider traverses the internet via hyperlinks
• The spider visits each HTML page and scoops up all the text on the page, assigning the page a unique document number
• The Search Engine then removes the tags, keeping only the text
• Finally the search index is created with each keyword stored along with information about what pages it was found on

So the Index table will look something like that:

se1 And the document table will look something like that:

Ranking the Matches

So after the Search Engine retrieve the pages (from the Index table) that match the search phrase which the user want to search for, it will rank these pages according to the following criteria:
Keyword Density – How frequently the search keywords are found in those pages
Keyword Proximity – Whether the search terms in a query are found close to each other in the web page.
Keyword Prominance – Pages that feature query words in titles, headings, emphasized text and initial paragraphs are said to have high keyword prominance.
Link Popularity – How many sites are linked to the page, and the authority of the sites that linked to the page.


Understanding how the search engine works is the first step towards SEO (Search Engine Optimization). In order for your site to rank high in search engine for your preferred keywords/keyphrases, you would have to optimize your webpages accordingly.

However, do bear in mind that, ultimately your webpages are meant to be read by humans, not machines. So do not cluster your webpages with keywords as that would become unreadable and google doesn’t like that too. Lastly, do note that google’s algorithm changes regularly so SEO is a continuous instead of one-off effort.