2.1. Natural and Paid Listings
Natural search result listings are listings that appear as search results without the payment of a special fee to the search engine provider. The goal of core SEO is to appear high in natural listings.
Paid listings take several forms. Some search engines (but not Google) accept pay for play search fees. Some consumer advocates frown upon these niche search engines because the appearance of a natural search result that is actually a paid listing can be confusing.
Googleand other first tier search enginestake the high road. If you purchase an advertisement keyed to search terms using Google AdWords, when your ad appears in response to a search query, it will be separate from the natural listings and clearly marked as sponsored.
As previously mentioned, the goal of core SEO is to obtain high natural listings. As the world of search has grown, however, the SEO discipline has also expanded. There's no longer any stigma associated with paid listings, particularly when using a program like AdWords that appropriately labels content. If paid listings help drive the traffic that you need in a cost effective fashion, they should be considered a valuable part of your extended SEO campaign management. You can find more information about effectively using the AdWords program in my book, Google Advertising Tools (http://www.oreilly.com/catalog/buildinggoogle/index.html), from O'Reilly.