What field is required in every document in MongoDB?

In every document stored in MongoDB, the _id field is required. This field serves as a unique identifier for each document within a collection. MongoDB automatically generates an ObjectId for the _id field if a value is not provided when the document is created. This ensures that every document can be uniquely identified and retrieved efficiently, which is essential for the integrity and performance of database operations.

While fields such as name, createdAt, and updatedAt can certainly be included in documents for added context or to track information, they are optional and do not have the same requirement status as the _id field. Each document must have a unique _id to maintain its place within the database and to support querying, updating, and deleting operations effectively.