What is MongoDB?

What is MongoDB?

MongoDB is a document database. Instead of storing data in tables and rows like a SQL database, it stores data in documents, which look a lot like JSON objects.

A record is a document

In MongoDB, a single record is called a document - a data structure made of field and value pairs, similar to a JSON object:

{
  title: "Post Title 1",
  body: "Body of post.",
  category: "News",
  likes: 1,
  tags: ["news", "events"],
  date: Date()
}

Field values can be numbers, strings, booleans, arrays, or even whole nested documents.

Why "document" database?

Documents map naturally to the objects you already use in code. A JavaScript object, a Python dict, or a Java class instance all look like a MongoDB document. This means no complex mapping layer between your code and the database.

BSON under the hood

MongoDB stores documents in a type of JSON format called BSON (Binary JSON). It's the binary serialization format MongoDB actually writes to disk, and it supports a few extra types that plain JSON can't express - like dates, ObjectIds, and 32-bit integers.

Key ideas

• MongoDB is non-relational (often called NoSQL).
• Data lives in flexible documents, not rigid tables.
• The format is JSON-like but stored as BSON.
• Document field values can be arrays or nested documents.

TL;DR

• MongoDB = document database, records are called documents.
• Documents look like JSON objects and are stored as BSON.
• No tables or fixed columns - just flexible documents.