Redis is an open-source, in-memory data structure store that functions as both a database and caching server, known for its high performance, replication capabilities, and support for multiple data types like lists, sets, and hashes. Unlike traditional databases, Redis operates without the need for strict schemas, making it flexible and efficient, particularly in handling multiple concurrent write requests through sharding. It is suitable for various use cases, including real-time applications, message queuing, session management, and caching. Redis can serve as a primary database or work alongside other databases to improve performance. The tutorial provides instructions on setting up Redis locally and via Redis Labs' cloud service, and demonstrates basic Redis commands and data structures using Node.js, emphasizing its versatility in data modeling and application in real-world scenarios.