Organic search results are listings on search engine results pages that appear because of their relevance to the search terms, as opposed to their being advertisements.
Gain organic traffic (as detailed in the article below):
Performing keyword research with tools like Google Keyword Planner
Optimizing your website
Using long tail keywords
Blogging often
Creating quality content
Getting social
Partaking in ethical link building
Playing by the rules
In contrast, non-organic search results may include pay per click advertising.