Introduction

Database operations are either data modification or query, as

Query – In MongoDB a query targets a specific collection of documents. Queries specify criteria, or conditions, that identify the documents that MongoDB returns to the clients. A query may include a projection that specifies the fields from the matching documents to return. You can optionally modify queries to impose limits, skips, and sort orders.
Data Modification – Data modification refers to operations that create, update, or delete data. In MongoDB, these operations modify the data of a single collection. For the update and delete operations, you can specify the criteria to select the documents to update or remove.