NoSQL is a term used to refer to a class of non-relational databases designed to handle large volumes of unstructured or semi-structured data in distributed systems. Unlike relational databases, which are based on predefined tables and schemas, NoSQL databases allow flexibility in data structure and horizontal scalability.

NoSQL databases are widely used in web and mobile applications, and are especially useful for handling large amounts of unstructured data, such as data generated by social networks and sensor data logs.

Some of the common features of NoSQL databases include horizontal scalability, the ability to store unstructured data, the ability to process large amounts of data in real time, the ability to handle distributed data, and flexibility in data structure.

In the field of artificial intelligence and machine learning, NoSQL databases are often used for the storage and processing of large data sets, such as training data for machine learning algorithms and data generated by IoT applications. The ability to scale horizontally and handle large volumes of unstructured data makes NoSQL databases a valuable tool for data processing in artificial intelligence and machine learning applications.