Creative destruction occurs when something new kills something older. A great example of this is personal computers. The industry, led by Microsoft and Intel, destroyed many mainframe computer companies, but in doing so, entrepreneurs created one of the most important inventions of this century.
Schumpeter goes so far as to say that the "process of creative destruction is the essential fact about capitalism." Unfortunately, while a great concept, this became one of the most overused buzzwords of the dotcom boom (and bust), with nearly every technology CEO talking about how creative destruction would replace the old economy with the new.