Relational Database Management Systems - RDBMS
Although most businesses manage their corporate data in relational database management systems (RDBMS), some businesses still operate application systems that use flat files for data storage.
Many of these old systems are"batch" systems that can't support online data transactions. A flat file can be stored on computer tape or on a hard drive of some sort.
Network databases such as IDMS became popular in the 1980s, when computers were much less powerful than the ones that exist today.