Search Engine
A search engine is a website that enables users to Query an Index of stored Web Pages gathered by a Crawler for information relevant to specific criteria expressed via a Keyword or Search Terms. The Rank of the information or website on the corresponding Search Engine Results Pages is determined by how relevant it may be as measured by the search engine’s Algorithm and/or payment made to the search engine by indexed sites.
Sites ranked exclusively by relevancy are known as Natural Listings or Organic Listings in contrast to the Paid Listings.