NodeJS is an evented I/O framework that allows JavaScript to be used for server-side web development. It uses the V8 JavaScript engine from Google Chrome. NoSQL databases like MongoDB, Redis, Cassandra, and Neo4J can integrate well with NodeJS through packages like Mongoose, Riak.js, node-redis, and node-neo4j. This allows real-time applications to be built combining the speed and scalability of NodeJS with flexible data storage of NoSQL databases.