A NoSQL Database is a type of database designed to handle large volumes of unstructured or semi-structured data. Unlike traditional relational databases, which use tables and fixed schemas, NoSQL databases can store data in various formats, such as key-value pairs, documents, or graphs. This flexibility allows for easier scaling and faster data retrieval, making them ideal for modern applications that require quick access to diverse data types. NoSQL databases are particularly popular in big data and real-time web applications. They support horizontal scaling, meaning you can add more servers to handle increased loads without significant changes to the existing system. This makes them a preferred choice for companies like Facebook and Google, which manage vast amounts of data daily.