An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers.
Stands for "Relational Database Management System." An RDBMS is a DBMS designed specifically for relational databases. Therefore, RDBMSes are a subset of DBMSes. A relational database refers to a database that stores data in a structured format, using rows and columns.