What is the difference between "sponsored" search engine results and "web" search engine results...
If you look around Yahoo's Help Section you will find the information below*. I was pleasantly surprised at their total honesty in their definitions.
Although the differences will vary with different search engines, the basic differences between "sponsored" and "web" results remain essentially the same.
Yahoo's explanation is as follows...
*What are the different sections on the Search results page?
We divided the Yahoo! Search results page into sections, so that it's clear and easy to find what you want. We'll show you the types of results that are relevant to your search, and you'll likely see some or all of the following:
Sponsor Results are sites that pay for placement in search results on terms that are relevant to their business. These listings are provided by Overture Services, a wholly owned subsidiary of Yahoo!, and appear on Yahoo! Search results pages and other sections of Yahoo!.
You'll see Sponsor Results when they're relevant to the specific search terms you used. For example, if you search for "digital cameras," you'll see Sponsor Results for web sites that provide information about or sell digital cameras. The Yahoo! Search results pages separate Sponsor Results from other results so you can tell them apart. For more information please see Sponsor Results or, if you are interested in participating in this program, please see Overture Advertising.
Web Results are the most relevant web pages found by Yahoo! Search in response to your search terms. Web Results are generated from the billions of web pages discovered, crawled, and indexed by Yahoo! Search. More than 99% of web pages in the Yahoo! Search index are included for free through the web crawl process. Web Results may also include links to sites that participate in the Content Acquisition Program (CAP). CAP enables content providers to submit web content directly to Yahoo! for review and inclusion in the Yahoo! Search index; content providers that participate in CAP through the Site Match(TM) program pay for these services. Participation in CAP does not guarantee placement or ranking in search results.
Why have free web listings at all. The answer is fairly simple. Relevancy is most necessary to bring you back again to use a search engine. Your results would lack relevancy and choice if only paid results were presented. In my opinion it would destroy the web as we have come to know it. Most of the web would become invisible without the free listings.