Database systems are software applications that manage, store, organize, and retrieve data in a structured format. These systems are used to ensure data integrity, security, and accessibility for various applications and users. Some key features of database systems include data modeling, query processing, transaction management, and data storage techniques. Researchers in this area focus on developing new technologies and techniques to improve the efficiency, scalability, and reliability of database systems. They also study topics such as data mining, data warehousing, big data analytics, and cloud computing in the context of database systems.