Databases

A database system is a software solution that enables storage, retrieval, and handling of the data entries. Each database system implements a Data model, which represents a set of concepts and rules that specify the architecture of a database.
The choice of data model depends heavily on the use case and specific properties of the data that is being stored. The approach of choosing the appropriate database based on the needs and requirements of the data and application is called Polyglot persistence.
There are many different databases designed for different Data and use cases.
All distributed system can only provide two out of three guarantees described in CAP Theorem.