MongoDB is a popular open-source document-oriented NoSQL database, designed for scalability and high availability. It stores data in flexible, JSON-like documents, allowing for easier and faster data retrieval, and its dynamic schema allows for more rapid development. MongoDB also supports advanced features such as automatic sharding and replication for increased fault tolerance and scalability. It can be used with various programming languages such as Python, Java, and Node.js, and can be installed on multiple operating systems including Windows, Linux, and Mac OS X. Due to its flexibility and scalability, MongoDB is a popular choice for applications that require frequent updates and dynamic data.