Set up a MongoDB Cluster using 3 Linux Instances

MongoDB is an open-source NoSQL database management program that offers an alternative to traditional relational databases. It is designed for working with large sets of distributed data and excels in high-volume data storage, ad-hoc queries, indexing, load balancing, aggregation, and server-side JavaScript execution. MongoDB's architecture is based on collections and documents instead of tables and rows, with documents consisting of key-value pairs. MongoDB supports various programming languages like C, C++, C#, Go, Java, Python, Ruby, and Swift. The database stores data as records made up of collections and documents, with documents structured as field and value pairs. MongoDB's benefits include scalability for structured and unstructured data, data integration for applications, complex data structure descriptions, and load balancing over multiple servers. Key features of MongoDB include replication for high availability, scalability through vertical and horizontal scaling, load balancing without a dedicated load balancer, schema-less database management, and support for ad-hoc queries.