Search Engine Optimization ( SEO ) affects only organic search results, not paid or sponsored results such as Google AdWords.

Those sites listed on the left of the Google search engine are what we called as "organic listing" - and whenever someone clicks on these links, the website's owner need not pay for anything - it's free traffic.

SEO is the process of search engine optimizing your web pages so that it matches the requirements that Google and other search engines has set up to consider rank.

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. Methods :

Getting indexed

The leading search engines, such as Google, Bing and Yahoo!, use crawlers to find pages for their algorithmic search results.

Pages that are linked from other search engine indexed pages do not need to be submitted because they are found automatically.

Google offers Google Webmaster Tools, for which an XML Sitemap feed can be created and submitted for free to ensure that all pages are found, especially pages that are not discoverable by automatically following links.

Preventing crawling

To avoid undesirable content in the search indexes, webmasters can instruct spiders not to crawl certain files or directories through the standard robots.txt file in the root directory of the domain.

Additionally, a page can be explicitly excluded from a search engine's database by using a meta tag specific to robots.

When a search engine visits a site, the robots .txt located in the root directory is the first file crawled.

The robots .txt file is then parsed, and will instruct the robot as to which pages are not to be crawled.

As a search engine crawler may keep a cached copy of this file, it may on occasion crawl pages a webmaster does not wish crawled.

Pages typically prevented from being crawled include login specific pages such as shopping carts and user-specific content such as search results from internal searches.

Increasing prominence :-

A variety of methods can increase the prominence of a webpage within the search results.

Cross linking between pages of the same website to provide more links to most important pages may improve its visibility.

Writing content that includes frequently searched keyword phrase, so as to be relevant to a wide variety of search queries will tend to increase traffic.

Updating content so as to keep search engines crawling back frequently can give additional weight to a site.

Adding relevant keywords to a web page's meta data, including the title tag and meta description, will tend to improve the relevancy of a site's search listings, thus increasing traffic.

URL normalization of web pages accessible via multiple urls, using the canonical link element or via 301 redirects can help make sure links to different versions of the url all count towards the page's link popularity score.