As my writing tools evolved with technology, so did my outlining tools. I used the Outline mode in Emacs on BSD, then the outlining mode in Concurrence on the NeXT platform. I then found myself in need of a new outlining tool as we moved to Mac OS X, so we adapted a little tool I’d written for my wife (to catalog our book collection) and OmniOutliner was born. (Crazy to think that I’ve now been using OmniOutliner for a quarter century!)