When we say natural or organic search we are referring to the listings on search engines - Google, Yahoo!, Bing (etc.) results pages.
Natural search is ordered by the relevance to the search terms, as opposed to non-organic search which generally refers to pay per click advertising.
So when you search a term on say Google, the top four listings will be paid advertisements, and the below listings will have been generated through natural search, where by Google pulls the most relevant listings to your search subject and lists them on the page in order of what is most connected to your search term.
When using Evvnt for your events marketing, Google search works off the content you supply. This is why we recommend you use as much detail as possible in your description, and create a strong event title. We then place your events on multiple targeted websites to generate your event to index on the first page of Google and further.