There are several different types of database management systems (DBMSs), each with its own unique characteristics and features. Here are seven common types of DBMSs:

1. Relational DBMS: This is the most widely used type of DBMS and is based on the relational model developed by Edgar F. Codd. In a relational DBMS, data is stored in tables, with rows representing individual records and columns representing the different attributes or fields of each record. Relationships between different tables can be established using keys.
2. Object-oriented DBMS: This type of DBMS is based on the object-oriented programming model, in which data is represented as objects with their own attributes and behaviors. Object-oriented DBMSs are well-suited for storing complex data structures and supporting the development of complex applications.
3. Hierarchical DBMS: This type of DBMS stores data in a hierarchical structure, with each record having a single parent record and potentially multiple child records. This model is well-suited for storing data that has a clear hierarchy or parent-child relationships.
4. Network DBMS: This type of DBMS is similar to the hierarchical model, but allows for multiple parent records for each child record. This allows for more complex relationships between records.
5. Relational object-oriented DBMS: This type of DBMS combines the features of both relational and object-oriented DBMSs, allowing for the storage of complex data structures and the establishment of relationships between different data sets.
6. NoSQL DBMS: This type of DBMS is designed to handle large amounts of unstructured data and is not based on the traditional relational model. NoSQL DBMSs are often used in big data and web applications.
7. In-memory DBMS: This type of DBMS stores data in the computer’s main memory rather than on a hard drive or other storage device. This allows for faster access to data but also requires a large amount of memory to store the data.