When you search anything on search engine, it gives you two types search results: organic search and paid search.
Organic search results are the listing on search engine that appear on search results page because of their relevant search terms that match the user’s search query. It is also called “Natural” search results.
Paid search results are basically advertisements which are paid by website owners for having their webpage display on top of the search results for certain keywords. So these listing show up when user search a query containing those keyword.
Organic search vs paid search:
Time: organic search ranking can take months or years, paid results are placed at the top of rankings as soon as you pay for advertisement.
Cost: if you are looking for quick results then paid search is better but if you are looking for the most cost effective results then organic search is better.
Evergreen: Organic search results have more evergreen presence than paid search results because they have the continued opportunity to high rank but Paid ads stop displaying as soon as you stop paying.