Elasticsearch index is a collection of JSON documents. Elasticsearch is a data store that may contain multiple indices. Each index may be divided into one or many types. A type is a group of similar documents. A type may contain multiple documents. In terms of database analogy, an index is a database and each of its types is a table. Each JSON document is a row in that table.
Indices created in Elasticsearch 6.0.0 or later may only contain a single mapping type.
Mapping types will be completely removed in Elasticsearch 7.0.0.
