In NoSQL key-value stores have been adopted because they promote easy scalability and flawless growth at rapid speed.
The basic concept is that a globally distributed hash table has keys that lead to the different database servers scattered all over the world.
Each data item is converted into a key using some unique formula
which is stored in the lookup table or directory. When the data
are needed, the key is converted into the location of the data and
accordingly data are retrieved.