When would you need to use the explicit $and operator in a MongoDB query?

The explicit $and operator is particularly useful when you need to combine multiple conditions that involve the same operator more than once in your query. For instance, if you have a scenario where you're querying documents based on several attributes and these attributes might require the same operator, using $and can ensure clarity and accuracy in your query.

For example, if you wanted to filter documents where "field1" is greater than 10 and "field2" is greater than 10, both tests would use the same comparison operator. By surrounding these conditions with $and, it can help to clearly express that all these conditions must be satisfied for a document to be included in the results.

Using $and becomes essential in more complex queries, allowing for more intricate logical structures and ensuring that the query remains understandable and maintainable. Therefore, its use is especially warranted in circumstances where the same operator is applied across multiple conditions.