Search engine optimization (SEO) involves achieving the highest position or ranking practical in the natural or organic listings as the main body of the search engine results pages (SERPS) across a range of specific combination of keywords (or keyphrases) entered by search engine users.
As well as listing pages which the search engine determines as relevant for the search performed based on the text it contains and other factors such as links to the page, the SERPs also contain other tools which searchers may find useful. Google terms these tools part of a strategy known as Universal or blended search.
The Natural or organic listings are the pages listing results from a search engine query which are displayed in a sequence according to relevance of match between the keyword phrase typed into a search engine and a web page according to a ranking algorithm used by the search engine.