What Is a Disruptive Technology?

Clayton Christensen now uses the term "disruptive innovation" over disruptive technology. So what exactly is a disruptive innovation then? This is a question that I struggled with for a long time until I read Robert Burgelman's book, Strategy is Destiny. He offers a great explanation on page 400. When reading the following, just substitute disruptive innovation for disruptive technology as this is essentially what Burgelman is describing:

"Disruptive technologies focus on a different subset of performance dimensions in a product's multidimensional performance space. These technologies are typically rejected by a company's existing customers and therefore are not further supported within the company's resource allocation process. Often the internal entrepreneurs associated with such initiatives leave the company to start a new one. After finding new customers interested in the different performance characteristics of the technology, performance on the other dimensions also improves over time. As a result, the customers that were earlier not interested are likely to eventually find the new technology good enough and may switch. This leaves the incumbent companies still working with the old technology in a difficult strategic situation."

Another really important point is that a disruptive innovation is not the same as a radical innovation. A radical innovation is just a major improvement along an existing performance trajectory. A disruptive innovation emphasizes a different performance dimension -- one that is not particulary important to incumbent firms' most profitable customers. This is often customization, convenience, or accessibility.