NoSQL databases have gained popularity since the early 21st century for handling big data and real-time web applications. They offer flexibility in handling structured, semi-structured, and unstructured data compared to relational databases. Key features of a NoSQL database include support for multiple data models, easy scaling with masterless architecture, multi-model capabilities for processing various types of data, distributed data management at global scale, and zero downtime through a masterless architecture. Companies dealing with diverse data types and building powerful web and cloud applications may benefit from using a NoSQL database that meets these requirements.