SEO (Search engine optimization) is simply "the use of search engines to draw traffic to a web site. It is the technique of attaining a higher ranking in search engines and directories via changes to a site to make it more search engine compatible". It is sometimes referred to more generally as search engine marketing, but in fact SEO (Search Engine Optimization) is just one facet of search engine marketing.
SEO specialists or "search engine optimizers" have sprung up to fill the need for these services over the past 8+ years. Most search engine optimizers will work either directly with the site administrator or with their web site designer to alter the site's code and content to ensure it gets the exposure it deserves in the most popular search engines and directories. The key to a successful SEO campaign is to find a specialist with a good track record, in an industry plagued with inexperienced and unethical providers.
Companies are spending tens of thousands of dollars on online and offline advertising, including banner ad, Pay Per Click (PPC) and viral marketing campaigns, so one could be forgiven for assuming that these companies do not need free traffic from the "organic" search engine listings.
However, by ignoring the most common method used by people browsing the Internet, these companies are sacrificing an enormous opportunity to attract more traffic to their sites. After all, brick and mortar companies don't refuse to put a sign up in front of their businesses just because they have put large amounts of money into promoting themselves via television advertising. Online companies, likewise, should not disregard optimizing their sites for search engines - a relatively inexpensive exercise - simply because they have put large amount of money into other marketing strategies.
Web site is a very large expense for these companies, ranging from a few thousand to hundreds of thousands of dollars. To invest such a massive amount of time, money and effort into an online presence and not ensure it can be found is like constructing a storefront without any doors.
It is obvious that companies need to invest in search engine optimization services to ensure their sites are made more search engine compatible and therefore visible to their target markets.