What is the function of the $ne operator in MongoDB?

The $ne operator in MongoDB is specifically designed to perform a "not equal to" comparison when querying documents in a collection. When you use the $ne operator in a query, it filters the documents by selecting those where the specified field does not match the provided value. This is particularly useful when you need to exclude certain values from your results.

For example, if you have a collection of products and you want to find all products that do not belong to a specific category, you would use the $ne operator to specify the category you want to exclude. This makes it an essential tool for creating more refined and precise queries.

The other options do not accurately describe the function of the $ne operator: it does not match all documents, nor does it match any documents indiscriminately. While it involves filtering, it is specifically about the inequality condition rather than general logical operations. Thus, the $ne operator stands out as a crucial component for queries requiring inequality comparisons.