Both organic search results and non-organic (ads) search results are used to optimize listings on search engines. Organic search result listings are generated through a search engines algorithms. These algorithms essentially say what is important and relevant, keeping in mind the intent of the search. Non-organic search results are based on listing purchases and highest bids.
There are many ways to boost the ranking of a listing on a search engine results list. One way is to use key terms within the content, focus keyword, and meta description of a listing that experiences a high volume of searches. This is seen as important to a search engines algorithms and have relevance to the term being searched. A term such as "home care" may experience a high volume of searches on various search engines such as Google or Bing; if the term "home care" was used within the titles, content, focus keyword, and meta description of a listing it would have a competitive advantage against other similar listings. Along with terms used within content, links, headings, and structure are also important for a listing to move up organically in search engines.