Mongo is a popular NoSQL database that stores data in a flexible, JSON-like format called BSON. This allows for easy storage and retrieval of complex data structures, making it suitable for applications that require scalability and quick access to large amounts of data. Unlike traditional relational databases, Mongo does not use tables and rows. Instead, it organizes data in collections and documents, which can vary in structure. This flexibility enables developers to adapt their data models as applications evolve, making Mongo a preferred choice for modern web and mobile applications.