In a 1995 article and a 1997 book, Clayton Christensen described the "innovator's dilemma": when you create something new and exciting, you get really good at making more and more money off of it, leaving you vulnerable to competition at the low end that totally undermines the whole market segment; Christensen deemed this "disruptive innovation." Silicon Valley fell in love with the phrase, making it completely meaningless along the way: now most people just use it to mean "out-compete". (Did Google really "disrupt" Yahoo's email business? Of course not.) Christensen hasn't helped, since he's built a whole cottage industry of books and seminars about how to disrupt just about anything.