NoSQL, short for "not only SQL," is a type of database management system that provides a non-relational approach to data storage and retrieval. Unlike traditional [[SQL]] databases, which use structured query language (SQL) and tabular relations to store data, NoSQL databases are designed to handle large volumes of unstructured or semi-structured data. NoSQL databases are characterized by their ability to scale horizontally, meaning they can handle increasing amounts of data by adding more servers to the database cluster. This makes them suitable for handling big data and high-traffic applications. There are several types of NoSQL databases, including: 1. Key-value stores: These databases store data as key-value pairs, where each value is associated with a unique key. They offer fast read and write operations but lack complex querying capabilities. 2. Document stores: Document-oriented databases store data in flexible, semi-structured formats like JSON or XML documents. They provide high flexibility and schema-less design, allowing for easy scaling and dynamic updates. 3. Column-family stores: Also known as wide column stores, these databases organize data into columns rather than rows. They are optimized for write-heavy workloads and can handle massive amounts of distributed data. 4. Graph databases: Graph databases focus on relationships between entities by using nodes (representing entities) and edges (representing relationships). They are highly efficient in traversing complex relationships in large datasets. NoSQL databases offer benefits such as horizontal scalability, high performance, flexible schema design, and support for unstructured or semi-structured data. However, they may not be suitable for all use cases, particularly those requiring complex relational queries or strict consistency guarantees. Overall, NoSQL databases have gained popularity due to their ability to handle modern application requirements involving big data processing, real-time analytics, content management systems, social networks, and other high-volume applications.