The good news about the most visible part of the Internet, the content pages of the world wide web, is that there are millions of available pages, waiting to show you information on an amazing variety of topics. The bad news about this content is that more then 50% of it is not even indexed by search engines.
When you need to find information about a particular subject, how do you know which pages to read? If you're like most people, you type in your browser the URL of one of the major search engines and start from there.
Search engines have a breef list of critical operations that allows them to provide relevant web results when searchers use their system to find information. They are special sites on the net that are designed to help people find the pages stored on other websites. There are some basic differences in the ways various search engines work, but they all perform four basic tasks:

Although a search engine's operations are not particularly lengthy, systems like Google, Yahoo!, AskJeeves and MSN are among the most complex, processing-intensive computers in the world, managing millions of calculations each second and funneling demands for information to an enormous group of users.
Search queries, the keywords that users type into the search box which contain terms and phrases best suited to your site carry extraordinary value. Experience has shown that search engine traffic can make (or break) an organization's success. Targeted visitors to a website can provide publicity, revenue and exposure like no other. Investing in SEO, whether through time or finances, can have an exceptional rate of return.
Why can't the search engines figure out my site without SEO?
Search engines are always working towards improving their technology to crawl the web more deeply and return increasingly relevant results to users. However, there is and will always be a limit to how search engines can operate. Whereas the right moves can net you thousands of visitors and attention, the wrong moves can hide or bury your site deep in the search results where visibility is minimal. In addition to making content available to search engines, SEO can also help boost rankings, so that content that has been found will be placed where searchers will more readily see it.
The online environment is becoming increasingly competitive and those companies who perform SEO will have a decided advantage in visitors and customers.