Relevance or Relevance ranking

Relevancy is the measure of how well the indexed page answers the question. Only the searcher can actually define how relevant a document is, in relation to their query: there is no way to automate it. When there are many query matches, the search engines must rank the results by relevance score, sorting the results listing so that the pages most likely to be useful will appear first. Varying algorithms are used to define relevancy.