In June 1970 Edgar F. Codd of IBM published "A Relational Model of Data for Large Shared Data Banks," Communications of the ACM, 13 (6) 377–387.
Codd’s model became widely accepted as the definitive model for relational database management systems. Codd postulated that data should be stored independently from hardware and that a programmer should use a nonprocedural language for accessing data. The crux of Codd’s solution was that data, rather than being stored in a hierarchical structure, would be stored in simple tables composed of rows and columns in which columns of like data would relate tables to one another. A database user or application, in Codd’s way of thinking, would not need to know the structure of the data in order to query that data.