NoSQL refers to non-relational databases that store data in flexible formats such as documents, key-value pairs, wide-column stores, or graphs. NoSQL systems prioritize scalability, high availability, and schema flexibility over strong structure or joins. They are commonly used in large-scale applications, real-time systems, and distributed architectures.
Why it matters
NoSQL databases handle massive workloads and evolving data structures better than traditional relational systems. They enable rapid iteration, horizontal scaling, and globally distributed storage models.
Examples
MongoDB for document storage, Redis as a key-value store, or Cassandra for wide-column storage. Lessons like SQL vs NoSQL Databases explain trade-offs.