The first step involves creating an index, because the index doesn't exist already. The index is created using the default number of shards. We will look at a concept called index templates – you can create templates for any new indexes. Sometimes, an index needs to be created on the fly, just like in this case, where the insertion of the first document triggers the creation of a new index. The index template kicks in and provides the matching template for the index while creating the new index. This helps in creating indexes in a controlled way, that is, with desired defaults, like the number of shards and type mappings for the types within them.

An index can be created beforehand as well. Elasticsearch has a separate index API (https://www.elastic.co/guide/en/elasticsearch/reference/current/indices.html) that deals with index-level operations. This includes create, delete, get, create mapping, and many more advanced operations.