Disruption is when the conditions of business change because of some new tool or way of doing things that renders another process completely or partially obsolete.
Currently, we still need people to transcribe print documents (and there are hundreds of people on Fiverr offering that as a service) because highly accurate OCR scanning is still not affordable to the general public. Once the software to convert printed documents to digital ones with a high degree of accuracy becomes widely available, those transcribers will become obsolete.
Similarly, the invention of the PC, the calculator, the iPhone, and other technologies has massively disrupted the ways in which we work and play.
This means that everyone needs to keep their skills up-to-date. Web developers and programmers are used to this constant self-reinvention, but other workers have been less exposed to this type of skills churn.
No more 'business as usual'
It is hard to predict what will be the next disruption. Blackberry could not have predicted the iPhone - but once it appeared and became mega-successful, they should have been looking at what features it had that made it so successful, and whether this had any implications for their product.
Companies can no longer expect to develop a product or service and keep on offering the same old, same old, year after year. They will get overtaken by newer competitors who have developed the 'killer app' of the moment.
The irony is that many organizations fail precisely because their leaders made good decisions for one particular point in time — the very same kind of good decisions that had made those companies successful for decades—and then they failed to recognize that times change, and past choices fade in appropriateness. These companies failed to reinvent themselves in the process, and were replaced by newer competitors unburdened by the legacy of success.