Documents, collections, and database

In order fully to understand how to use MongoDB, it is important to discuss the terms used to describe MongoDB data structures: documents, fields, and collections. The following table summarizes these three terms by way of illustration. In this table, we also draw an equivalence between MongoDB and RDBMS (Relational Database Management Systems):

MongoDB	RDBMS	Illustration
Document	Row
Field	Column
Collection	Table

In the preceding example, we see a document that represents information about a member whose name is Smith. Within the document are fields, the example highlighted being cost. Documents that are stored together for a single logical purpose represent a collection. A MongoDB database consists of one or more collections.