AutoLISP
AutoCAD rose to be the dominant computer drafting program for several reasons, including generalization (it was not targeted to a single profession and therefore was adopted by nearly every profession that uses drafting), widespread piracy (of which it is debatable whether its publisher secretly encouraged), and constant incorporation of other drafting programs' best concepts (AutoCAD is not necessarily the best program for any given functionality, but it has nearly every function otherwise available). One of the lesser-thought-of reasons for AutoCAD‘s dominance is the powerful customization capability imparted by its native programming language, AutoLISP. Based on the common LISP programming language, AutoLISP offers the ability for end-users to “scratch what itches” and expand the already impressive functionality of AutoCAD. Whether creating automation subroutines or interface customization, AutoLISP creates an environment with nearly limitless possibilities.
I am an AutoLISP programmer.