Which operator is used to find a subdocument that matches specific criteria in an array?

The operator that is used to find a subdocument matching specific criteria in an array is $elemMatch. This operator is particularly useful when working with documents that contain arrays of embedded documents. When you want to retrieve documents from a collection where at least one element in the array matches all specified criteria, $elemMatch allows you to express that requirement clearly.

For instance, if you have a document structure where a field contains an array of objects, and you want to filter those documents based on multiple properties of one of the objects within that array, $elemMatch is the optimal choice. It ensures that all conditions specified in the $elemMatch document must be met by a single element of the array, making it powerful for complex queries.

Other operators serve different purposes. The $and operator is used to combine multiple query conditions and requires all conditions to be true but does not specifically target elements within an array. The $or operator allows for any of the specified conditions to be true, which again is broader and not specifically for subdocuments within arrays. The $not operator is used to negate conditions, making it unsuitable for directly matching array elements on criteria.

In summary, $elemMatch stands out as the appropriate operator for querying subdocuments within arrays, ensuring precise