ObjectID is automatically generated by the database drivers, and will be assigned to the _id field of each document. ObjectID can be considered globally unique for all practical purposes. ObjectID encodes the timestamp of its creation time, which may be used for queries or to sort by creation time.

Does MongoDB create ObjectId?

To create a new objectID manually within the MongoDB you can declare objectId as a method. In simple words, we can say that object ID is a unique identifier for each record. In the below image you can observe that we are declaring a variable having object ID method as a value and it will return unique hexadecimal.

How does MongoDB ObjectId work?

Every document in the collection has an “_id” field that is used to uniquely identify the document in a particular collection it acts as the primary key for the documents in the collection. The next 3 bytes are the machine Id on which the MongoDB server is running. ...