How does an embedded document function in MongoDB?

An embedded document in MongoDB plays a crucial role in structuring data by allowing the nesting of related information within a single parent document. This means that related fields and values can be grouped together, which not only enhances data organization but also improves query performance. When data is related, such as an order and its associated items, embedding them into a single document allows for efficient retrieval without the need for multiple queries or joins, which are typically necessary in relational databases.

This feature aligns well with MongoDB's design principles, catering to use cases where data is inherently related and accessed together. By organizing data in this way, it facilitates faster read operations and defines a clear hierarchical relationship between entities in the document.

In contrast, the other choices do not capture the function of an embedded document. For instance, treating it as a separate collection does not reflect the strategy of nesting data. Increasing redundancy is more associated with certain design choices in database architecture, rather than the primary function of embedding. Lastly, the notion of compressing data for storage efficiency pertains more to how data is stored rather than the structural advantages of embedding documents within MongoDB.