A key-value store is a type of database that uses a simple data model to store information. In this model, data is organized as pairs of keys and values, where each key is unique and acts as an identifier for its corresponding value. This structure allows for quick retrieval of data, making key-value stores efficient for applications that require fast access to information. These databases are often used in scenarios where scalability and performance are crucial, such as in web applications and caching systems. Popular examples of key-value stores include Redis, Amazon DynamoDB, and Riak. Their simplicity and speed make them suitable for various use cases.