Well, fundamentally: information. On the spectrum from theoretic to applied, this is about the nature of information, its relationship to physical reality; to more applied things; viewing software as the creation and manipulation of information. A software engineer applies the principles of engineering to software. Some of these principles are inherited from engineering in the broader sense; some are specific to software.
From a mathematical perspective, I seek to build an intellectual framework of all the above by formulating precise definitions and relationships, and sets and subsets.
* Information is the only resource that grows as it is used.
Who do I write for?
Myself, to be honest.