In recent years there was a high demand for massively distributed databases with high partition tolerance but according to the CAP theorem it is impossible for a distributed system to simultaneously provide consistency, availability and partition tolerance guarantees. A distributed system can satisfy any two of these guarantees at the same time, but not all three. For that reason many NoSQL databases are using what is called <answer>eventual consistency</answer> to provide both availability and partition tolerance guarantees with a reduced level of data consistency.
What is used to offer a balance in guarantees?
eventual consistency