This information applies to version 2.x of Elasticsearch. For the most up to date information, see the current version of the Elasticsearch Reference.
- The ability to rank results by how relevant they are to the given query, whether relevance is calculated using TF/IDF (see What Is Relevance?), proximity to a geolocation, fuzzy similarity, or some other algorithm.
- The process of converting a block of text into distinct, normalized tokens (see Analysis and Analyzers) in order to (a) create an inverted index and (b) query the inverted index.