Search Engine Optimization (SEO) is the technique of improving the visibility of a web site or a web page in search engines. Higher the visibility high is the traffic. Search engines are not humans neither they are intelligent creatures. Search engines are simply text-driven machines. More the relevant scattered text more likeness they build of you web site.
How Search Engines Work
Search engines crawl the Web, looking at particular site items (mainly text) to get an idea what a site is about. Search engines perform these activities in order to deliver search results:
After a page is crawled, the next step is to index its content. The indexed page is stored in 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. Sometimes crawlers might not get the right meaning of a page so by optimizing the page makes it easier to classify pages correctly and get higher rankings.
When a search request comes, the search engine processes the web page (compares the search string in the search request with the indexed pages in the database). Since it is likely that more than one page (practically it is millions of pages) contains the search string, the search engine starts calculating the relevancy of each of the pages in its index to the search string.
There are various algorithms to calculate relevancy. Each of these algorithms has different relative weights for common factors like keyword density, links, or metatags. That is why different search engines give different search results pages for the same search string. What is more, it is a known fact that all major search engines, like Yahoo!, Google, MSN, etc. periodically change their algorithms and if you want to keep at the top, you also need to adapt your pages to the latest changes. This is one reason (the other is your competitors) to devote permanent efforts to SEO, if you'd like to be at the top.
The last step in search engines' activity is retrieving the results. Basically, it is nothing more than simply displaying them in the browser – i.e. the endless pages of search results that are sorted from the most relevant to the least relevant sites.
Keeping in mind how the search engine works a successful search engine optimization campaign will contain these listed points:A. In the Web Page context