What does the `count()` method do in MongoDB?

The count() method in MongoDB is specifically designed to count the number of documents that match a given query. This functionality allows users to retrieve statistics on subsets of data based on specified criteria. When you provide a query to the count() method, it evaluates that query against the collection and returns the total number of documents that fulfill the conditions outlined in the query.

This is particularly useful in a variety of application scenarios, such as verifying the existence of certain records, gauging the response of filtering operations, or understanding the distribution of data points across different categories.

By contrast, counting all documents in a database or the total number of databases is not the purpose of the count() method. Moreover, counting the number of fields in a collection does not apply, as the method focuses solely on counting documents based on provided query filters.