NoSQL for Big Data focuses on databases that are designed to handle large volumes of unstructured or semi-structured data with high scalability and performance. Cassandra and Couchbase are two popular NoSQL databases used in Big Data environments. Cassandra is known for its decentralized architecture and ability to scale horizontally across many nodes, making it ideal for applications that require high availability and fault tolerance. Couchbase, on the other hand, combines document-oriented and key-value data models, offering real-time data processing, flexible queries, and automatic scaling. Both databases provide efficient solutions for managing vast amounts of data in distributed environments.