MongoDB Documentation, Release 3.0.4 Distributed Queries (page 69) Describes how sharded clusters and replica sets affect the performance of read opera- tions. Read Operations Overview Query Interface For query operations, MongoDB provides a db.collection.find() method. The method accepts both the query criteria and projections and returns a cursor (page 64) to the matching documents. You can optionally modify the query to impose limits, skips, and sort orders. The following diagram highlights the components of a MongoDB query operation: The next diagram shows the same query in SQL: 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. The projection limits the amount of data that MongoDB returns to the client over the network. Read operations, or queries , retrieve data stored in the database. In MongoDB, queries select documents from a single collection . Example See 61 3.2. MongoDB CRUD Concepts SQL to MongoDB Mapping Chart (page 131) for additional examples of MongoDB queries and the corresponding SQL statements. This query selects the documents in the users collection that match the condition age is greater than 18 . To specify the greater than condition, query criteria uses the greater than (i.e. $gt ) query selection operator . The query returns at most 5 matching documents (or more precisely, a cursor to those documents). The matching documents will return with only the _id , name and address fields. See Projections (page 62) for details. db.users.find( { age: { $gt: 18 } }, { name: 1, address: 1 } ).limit(5)