Basics about Search Engine Optimization

What are Search Engines?

Search engines are programs that search document for specified keywords and return a list of document where keywords were found.

These are designed to search for information on World Wide Web. The search results generally presented in a line of results referred to SERP (search engine results page).

Search engines are very critical key element to find out specific and relevant information through huge extend of World Wide Web.

For example: google, yahoo, bing, msn etc

How Search Engine works?

Search engines have robots (spiders, crawlers) that scour the internet and send back the results and links to the search engines. Usually a webpage may have pdf, jpg, image or other files, but search engines need to crawl all types of webpage so they use the best paths-links. 

There are total five steps of working:

Crawling: 

First of all search engines crawl the web to see what is there on webpage. So a piece of software called robots crawl the whole webpage and follow links from one page to another. Crawlers can reach millions of interconnected documents following links. 

Spider (robots, crawler):

A set of computer program that browses www in methodical way and automatically scan the webpage & website for updated content & downloaded a copy of its data centre to index.

Every search engines have their robots like google has googlebot, yahoo has yahoo slurp and bing has bingbot etc.

Indexing:

The process of indexing is identifying the words and expressions that describe the page and assigns the page to a particular keyword.

After search engine index everything they found on the way according to their relevancy and important links. And indexed page is stored in a giant database from where it can later be retrieved. 

Processing:

When visitors enter for a search query, the search engine processes it. They compare the search request with the indexed pages in database. They search the relevant information from their database as we search meaning of a specific word from the dictionary.

Calculating Relevancy:

It might be possible that more than one page contains search string. So search engines starts calculating relevancy of each page according to their unique contain and important links. They calculate relevancy with the help of various algorithms like keyword density, links, Meta tags etc.

Websites with unique and updated contents get higher preference than others.

Retrieving:

After choose pages for search query, they display the results in the browser with most important sites to least important sites.