Key-Value Store (or Key-Value Database) is a type of database that stores data as a set of unique identifiers (Key), each of which holds a value (Value). This value can be a primitive type, such as integer or text; or a complex data type, usually stored as JSON document.
Disclaimer: Picture above is an artist's impression and is not accurate representation of mechanics of Key-Value Stores :)
All Use Cases
Piotr Kononow