I wanted to use the mongodb database, but I noticed that there are two different databases with either their own website and installation methods: mongodb and mongoose. So I
Mongo is NoSQL Database.
If you don't want to use any ORM for your data models then you can also use native driver mongo.js: https://github.com/mongodb/node-mongodb-native.
Mongoose is one of the orm's who give us functionality to access the mongo data with easily understandable queries.
Mongoose plays as a role of abstraction over your database model.