It is well known that, at the present, a huge amount of information, often referred as Big Data, is processed by each domain of modern society. Big data are well defined by the seven dimensions: Volume, Velocity, Variety, Variability, Veracity, Visualization and Value. The traditional database management systems cannot handle the requirements of high availability, scalability and reliability emerged with Big Data. The good news is that we are now in the age of NoSQL databases. NoSQL do not have a fixed structure, they have a flexible structure and are suited for storing unstructured data produced in a large scale in various field. This work outlines the four main types of NoSQL databases and presents some of their representative solutions