The question posed in the title of this article seems very simple to answer, and even in their own words many of the people reading this might describe what they think is IT. And the fact is that their definition is likely to be very correct, although perhaps incomplete.
The often used IT acronym comes from the words Information Technology. When most people think of Information Technology, focuses more on "Technology" and less on "Information" which is, to me, even more important. By (simple) definition "Technology" is a tool for a purpose, therefore we are left to ask ourselves what is that purpose and not to lose focus on it. And that purpose is about the information itself; the gathering, processing, transmission, storage and, in some cases, interpretation of that information in order to make better decisions.