The letters SEO stand for Search Engine Optimization. No one will be interested in "optimizing a search engine", the real meaning of SEO is to optimize a Web Page for search engines aiming to improve the ranking of a website for a keyword for search engines.
I don't care what you have read, if your optimization tactics are in breach of the Google Webmaster Guidelines, or other Search Engine
rules, any success you may be getting is only temporary. Don't take my word on this, read the Google facts before wasting your valuable time and money.
Google indexes pages on the Web by using what are commonly known as "robots", "spiders" or "crawlers". GoogleBot, Google's famous search engine spider, uses links on web pages as a sort of freeway.
It travels from Web site to Web site by following links. When Google finds a new web page, Google will "crawl" the HTML code on the page and transport it back to one of its datacenters. Google's "FreshBot" may visit "indexed websites" everyday in order to keep the index fresh and present. How often this is done varies wildly from site to site.
Google's database maintain billions of pages and grows from hour to hour. They use a proprietary formula (alogorithm) to "score" the relevancy of websites for each search query. The highest ranking, or "most relevant" websites for a specific query are listed first in the search results. The first 10 positions in a search engine like Google are getting about 90% of the total search traffic.
Take for example the search query "used cars". Imagine Google maintains two pages in it's index containing the term "used cars" (in reality it would have hundreds of thousands or even millions). Now imagine the first page displays the following headline, "Used Cars: best offer". The second page it titled "Cars for Sale", but mentions "used cars" (in passing) in the text of the article. Google will most likely rank the first page as "more relevant". The first page would appear above the second in the search results.
Some other factors that seem to be major contributing factors in the algorithm of Google and other major search engines include:
Google awards "points" for how often keywords are mentioned, how prominent they are on the page and the location on the page. It is important not to overdo repetitive keywords… Google filters these sites out as "keyword spamming", they could be even banned from Google's index.
It is important to design your site with clean code (e.g. do not use frames). For the most part, the more text you have on your site, the better you will rank. This is because Google believes you are providing good information to you visitors. In essence, you are becoming an authority on a topic.