A database that features fewer consistency restrictions than conventional relational databases. While most often called NoSQL databases, these databases are sometimes also referred to as “Not Only SQL” databases to reflect that SQL queries can be used in some cases.

NoSQL databases feature highly optimized key-value data designed for quick retrieval and appending operations, and they can offer substantial performance benefits over relational databases in terms of latency and throughput. As a result they’ve become quite popular recently, particularly in use with Big Data, cloud computing and real-time web applications.