I In web search engines, organic search results are query results that are calculated strictly algorithmically and are not influenced by advertiser payments. These differ from different types of sponsored results, whether they are explicit pay-per-click ads, shopping results, or other results where the search engine is paid either to display the result or to click on the result.
The search engines Google, Yahoo! And Bing inserts advertising on their search results pages. By law, advertising must be distinguished from organic results. This is done with various differences in background, text, link colors and/or page layout. However, a 2004 study found that most search engine users cannot tell the difference between the two.
Because so few average consumers (38% according to the Pew Research Center) realize that many of the top “results” on search engine results pages (SERPs) are advertisements, the search engine optimization industry is beginning to differentiate between advertisements and natural results. [ citation needed] The perspective among users was that all results were in fact “results”. So the “organic” qualifier was invented to distinguish non-ad search results from ads. It has been in use since at least 2004.
The distinction is important (the word “organic” has many metaphorical uses), the term is now widely used in the website optimization and web marketing industry. As of July 2009, the term “organic search” is now used outside of the specialized web marketing industry, even frequently used by Google (for example, throughout the Google Analytics site).
Google claims that their users click on (organic) search results more often than ads, essentially refuting the research cited above. A 2012 Google study found that 81% of ad impressions and 66% of ad clicks occur when there is no related organic search result on the first page. Research shows that searchers can have ad bias unless the ads are relevant to the searcher’s needs or intent. 
The same report and others going back to 1997 by Pew show that users avoid clicking on “results” they know are ads.
According to a June 2013 study by Chitika, 9 out of 10 searchers do not go beyond the first page of Google’s organic search results, a claim often cited by the search engine optimization (SEO) industry to justify optimizing websites for organic search. [6 ]  Organic SEO describes the use of certain strategies or tools to elevate a website’s content in the “free” search results.
Users can prevent ads from appearing in search results and list only organic results using browser add-ons and plug-ins. Other browsers may have different tools designed to block ads.
Organic search engine optimization is the process of improving the rank of websites in organic search results.