MongoDB is a popular NoSQL database system renowned for its flexibility and scalability. It uses a document-oriented model, storing data in JSON-like BSON format, allowing for dynamic schemas and easy data manipulation. MongoDB's distributed architecture supports horizontal scaling, ensuring high availability and performance. It's widely utilized for applications requiring real-time data access and complex data structures. Its features include automatic sharding, replication, and support for geospatial data, making it a versatile choice for a broad range of industries, from e-commerce and social media to IoT and big data analytics.