The introduction of digital technology has caused a switch to computer aided drafting, or CAD.
The origins of the detailed plans of structures common to modern times was in the Renaissance, when artists made detailed sketches of classical buildings and began planning buildings that they imagined. Builders were expected to follow the illustration and work out the details.
As building became more complex, the art of drafting the plans advanced so that everything was spelled out in detail. Creating detailed plans helps to avoid construction delays, to make cost estimates and to help the builder decide to commit to a project.
Eventually, the conventions used in modern architecture were adopted by the architects who prepared the plans. These are combined to create comprehensive plans for the building, used at stages to solve engineering problems or construction guides.
Copies of plans at first needed to be laboriously redrawn by hand, which was done on special paper such as vellum that could not shrink or stretch.