This document discusses different types of database management systems including hierarchical, network, entity-relationship, relational, and object-oriented databases. A database management system (DBMS) is software that allows users to create, organize, and manage databases and perform operations like creating, inserting, deleting, updating, and retrieving data. Each type of DBMS stores and connects data in a different way, with relational databases using tables to represent data and relationships and object-oriented databases representing entities as classes with attributes, behaviors, and communicating objects.