What is the purpose of referencing in MongoDB?

The purpose of referencing in MongoDB is to save the _id field of one document in another as a link. This technique allows you to establish relationships between documents in different collections, enabling you to maintain a separation of concerns and keep the data structured and organized.

By using references, you can avoid data duplication while still being able to relate entities. For example, if you have a collection of users and a separate collection of orders, instead of duplicating user information in every order document, you can simply store the user’s _id in the orders collection. This not only saves storage space but also makes it easier to update user data in one location rather than in multiple places.

In contrast, storing all data in a single document can lead to challenges with scalability and flexibility. Normalizing data is also related to reducing redundancy but is more about the design of schemas rather than the principle of referencing. Additionally, encrypting sensitive information serves a different purpose focused on security rather than structuring data relationships.