A record in MongoDB is a document, which is a data structure composed of field and value pairs. MongoDB documents are similar to JSON objects. The values of fields may include other documents, arrays, and arrays of documents.
The advantages of using documents are:
Documents correspond to native data types in many programming languages.
Embedded documents and arrays reduce need for expensive joins.
Dynamic schema supports fluent polymorphism.
MongoDB stores documents in collections. Collections are analogous to tables in relational databases.
In addition to collections, MongoDB supports:
MongoDB provides high performance data persistence. In particular,
Support for embedded data models reduces I/O activity on database system.
Indexes support faster queries and can include keys from embedded documents and arrays.
The MongoDB Query API supports read and write operations (CRUD) as well as:
MongoDB's replication facility, called replica set, provides:
A replica set is a group of MongoDB servers that maintain the same data set, providing redundancy and increasing data availability.
MongoDB provides horizontal scalability as part of its core functionality:
MongoDB supports multiple storage engines:
In addition, MongoDB provides pluggable storage engine API that allows third parties to develop storage engines for MongoDB.