Entity-relationship modelling

In March 1976 the first issue of ACM Transactions on Database Systems carried a paper by Peter Chen, then at MIT: “The Entity-Relationship Model: Toward a Unified View of Data”. Designers at the time argued over network, hierarchical and relational schemas as if the choice came first.

Chen's point was that it does not. First describe the things the business cares about and how they relate, in a diagram anyone can read; translate it into tables afterwards. Fifty years later most database design still starts with an ER diagram on a whiteboard.