In this article you will learn how to integrate ElasticSearch into a Rails application. A full-text search engine examines all of the words in every stored document as it tries to match search criteria (text specified by a user) wikipedia. For example, if you want to find articles that talk about Rails, you might search using the term “rails”. If you don’t have a special indexing technique, it means fully scanning all records to find matches, which will be extremely inefficient. One way to solve this is an “inverted index” that maps the words in the content of all records to its location in the database.