Edgar F. Codd, a researcher at IBM, invented the relational model for database management. Before Codd, data was stored in rigid hierarchies that were difficult to search. Codd’s model organized data into tables that could be 'related' to one another. This led to the development of SQL (Structured Query Language). This invisible invention is the foundation of almost every digital service we use today—from bank accounts and airline reservations to social media feeds and the entire e-commerce industry.