NoSQL

A broad category of non-relational database systems designed to handle large volumes of unstructured, semi-structured, or structured data. Unlike traditional relational databases, NoSQL systems do not rely on fixed schemas or SQL-based querying. They include document stores (e.g., MongoDB), key–value stores (e.g., Redis), wide-column stores (e.g., Cassandra), and graph databases (e.g., Neo4j). NoSQL databases are highly scalable, flexible, and ideal for real-time applications, big data, and distributed systems.