A relational DBMS (RDBMS) is a type of database management system that organizes data into tables, which consist of rows and columns. Each table represents a different entity, and relationships between these tables are established through keys. This structure allows for efficient data retrieval and manipulation using a standardized language called SQL (Structured Query Language). RDBMSs are widely used in various applications, from small businesses to large enterprises, due to their ability to maintain data integrity and support complex queries. Popular examples of RDBMS include MySQL, PostgreSQL, and Oracle Database, each offering unique features to manage and analyze data effectively.