Introduction:

MongoDB is schemaless free and open-source cross-platform NoSQL database management system, that supports horizontal scaling using sharding and fault-tolerent using replication.

Terminology:
If you are coming from RDBMS you may find that MongoDB uses different terminology for tables and tuples.
i.e.,

RDBMS MongoDB
database database
table collection
row document or BSON document
column field
index index

for more RDBMS to MongoDB terms check offical documentation on SQL to MongoDB Mapping Chart.

1. Getting familiar with JSON & BSON:

To get started with MongoDB, one must get familiar himself/herself with JSON, as MongoDB use BSON to store documents.
i.e., sample Student document (record) in MongoDB may look like as below:

{
    name: "s1",
    dateOfBirth: ISODate("1997-10-01T00:00:00.000Z"),
    rollNumber: 21,
    subjects: ["English", "Maths", "Physics", "Computer Science"],
    marks: [
        {
            subject: "English",
            grade: "B"
        },
        {
            subject: "Maths",
            grade: "B"
        },
        {
            subject: "Physics",
            grade: "A"
        },
        {
            subject: "Computer Science",
            grade: "A"
        }
    ]
}

In the above BSON document marks field contains array of sub-documents also called embedded-documents for more info check data modeling patterns (in RDBMS one may use reference table), also note that in the above document dateOfBirth is stored in ISODate format, which is a Date data type provided by BSON, you may also want to check BSON Types

2. Hands-on with MongoDB:

There are more than one way, you can get get started by trying MongoDB

  • Install Locally: For advance users, head to MongoDB Installation Document to install MongoDB Server and MongoDB shell on your local system
  • Try MongoDB Atlas: MongoDB Atlas is cloud hosted Database as a service, which provides a free sandbox account, where one can try mongodb without installing mongodb on his/her local system, its good if you are not an advance user.
  • Interacting with MongoDB via GUI: If you are coming from RDBMS like MySQL or SQL Server, you might me more used to with MySQL Workbench or SQL Server Management Studio, MongoDB Compass is the official GUI client for MongoDB to visually explore and run queries to interact with your data.
  • There are list of other MongoDB products that you may want to try in no particular order i.e., MongoDB Cloud, MongoDB Ops Manager, MongoDB Stitch, MogoDB BI Connector, etc.,.

3. MongoDB Online Resources:

There exists extensive lists of online learning materials provided by MongoDB:

4. Connect to MongoDB Socially:

Connecting to MongoDB channels socially means you are engaged in group discussions with users around the world to solve specific problems.

5. Stay Up-to-date:

Last but not least you may want to stay updated with latest news on mongodb, if so subscribe to the MongoDB news, by browsing mongodb.com scroll down to the section Get MongoDB Email Updates enter your email address and submit, you will start receiving latest news about mongodb.