Edgar Frank Codd, a British researcher at the IBM San Jose Research Laboratory, published in 1970 "A Relational Model of Data for Large Shared Data Banks", proposing to organize information into tables (relations) composed of rows and columns, dispensing with the hierarchical and network models dominant until then, which required knowing the physical storage structure in advance to query the data. Codd also formulates relational algebra, a set of formal mathematical operations — selection, projection, union, intersection, Cartesian product — that allow data to be queried and combined declaratively: the user specifies what information is needed, not how to retrieve it step by step. This separation between query logic and physical implementation is the article's central conceptual innovation. Despite its mathematical rigor, IBM — which dominated the hierarchical database market with its IMS system — takes years to commercialize Codd's idea; it is finally in 1979 that Lawrence Ellison, directly inspired by Codd's article, launches the first commercial version of Oracle. SQL (Structured Query Language), developed at IBM from 1974 onward as a practical implementation of the relational model, becomes the universal standard for querying databases, present in virtually every business, banking, or web information management system of subsequent decades.