A MongoDB database contains a set of collections. A collection is a set of documents and is similar to a table in a relational database. MongoDB stores records as documents that are similar to rows in a relational database. A document contains fields that are similar to columns in a relational database. A document can have a dynamic schema. A document in a collection does not need to have the same set of fields or structure as another document in the same collection. A document can also contain nested documents.

The following schema provides a sample MongoDB document from the collection called Product:

{
  sku: "111445GB3",
  title: "CM Phone",
  description: "The best in the world.",

  manufacture_details: {
    model_number: "CMP",
    release_date: new ISODate("2011-07-17T22:14:15.656Z")
  },

  shipping_details: {
    weight: 350,
    width: 10,
    height: 10,
    depth: 1
  },

  quantity: 99,

  pricing: [
    {region: "North America",
					cost_price: 1000,
				 sale_price:	1200},
				{region: "Europe",
					cost_price: 1200,
				 sale_price:	1500}
		]

}

In the example, sku, title, description, quantity, manufacture_details, shipping_details, and pricing are fields. The fields manufacture_details and shipping_details are nested document type fields and pricing is an array type field.