The term "Human Factors" is hard to define. For that reason, it has earned more than a single definition. It reaches out to many areas of study including jurisprudence, psychology, criminal motivation, operator error (it started out as "pilot error" at the end of WWII), from whence it became a synonym for poor design, and so through "ergonomics", and in later days, the grimmer stuff of terrorism and its motivations and techniques.

I frequently use a prepared sheet of paper which I take to such events as depositions, trials and seminars which states that human factors encompasses [That which can reasonably be expected of human beings in response to challenges with which they are presented and based on general and individual human characteristics]... which is still a good start.

However, I must confess that it is but a beginning. The World Trade Center fell because of human factors of a nature which were rarely considered a few years ago. It's a long way from a trip-and-fall to a global crisis, yet each has its place in our present world and ultimately all acts of humankind are part of that spectrum of experience. If the harmless-looking dying match is ignored a million acre inferno may result. Every step taken by humans and the results those steps produce, are part of human factors... but perhaps I have said enough for a beginning.

More will unquestionably follow...