In Elasticsearch terminology, adding (or creating) a document to a type within an index of Elasticsearch is called an indexing operation. Essentially, it involves adding the document to the index by parsing all the fields within the document and building the inverted index. This is why this operation is known as an indexing operation.

There are two ways we can index a document:

• Indexing a document by providing an ID
• Indexing a document without providing an ID