The Nature of Software
Nature of Software
This would be the title of a blog and I do not know what are the slight differences between the two.
Exactly what StoneyB says, with no determiner/qualification, it would mean the natural world and with the, it refers to the fundamental quality.
I'll add a little bit to this - when it comes to the title, the authors are quite flexible in grammar rules. I have read several titles without definite/indefinite articles though they all required.