The purpose of the study is to deepen within NoSQL databases and investigate what tasks the different NoSQL groups fit best in a social network, such as Facebook and Twitter. The data is, for example, about the storage of personal data or social networking. There are four different types of NoSQL databases: column databases, graph databases, key value databases and document databases. The question is which NoSQL database should be chosen for a particular task in a given social network. When developing a social network that requires data storage, it is important to know what kind of database should be used for a certain type of task. In order to answer the questions, an investigation has been made of what previous research has reached. There has also been a practical study of all four NoSQL groups in an experiment with storing user information, messages and friends.