What is Disruptive technology???

A disruptive technology or disruptive innovation is a term describing a technological innovation, product, or service that uses a "disruptive" strategy, rather than a "revolutionary" or "sustaining" strategy, to overturn the existing dominant technologies or status quo products in a market. Disruptive innovations can be broadly classified into low-end and new-market disruptive innovations. A new-market disruptive innovation is often aimed at non-consumption, whereas a lower-end disruptive innovation is aimed at mainstream customers who were ignored by established companies. It has been systematically shown to the research community that most disruptive innovations are in a minority compared to revolutionary innovations which introduce an innovation of higher performance to the market. Examples of true disruptive innovations, ie. innovations that are lower in performance and lower cost, succeeding are rare. Occasionally, a disruptive technology comes to dominate an existing market by either filling a role in a new market that the older technology could not fill (as cheaper, lower capacity but smaller-sized flash memory is doing for personal data storage in the 2000s) or by successively moving up-market through performance improvements until finally displacing the market incumbents (as digital photography has begun to replace film photography).
By contrast, a "revolutionary technology" introduces products with highly improved new features into the market. This is the innovation that most often replaces the incumbent. In addition, a "sustaining technology or innovation" improves product performance of established products. Sustaining technologies are often incremental; however, they can also be radical or discontinuous.

The theory

Christensen distinguishes between "low-end disruption" which targets customers who do not need the full performance valued by customers at the high-end of the market and "new-market disruption" which targets customers who have needs that were previously unserved by existing incumbents.
"Low-end disruption" occurs when the rate at which products improve exceeds the rate at which customers can adopt the new performance. Therefore, at some point the performance of the product overshoots the needs of certain customer segments. At this point, a disruptive technology may enter the market and provide a product which has lower performance than the incumbent but which exceeds the requirements of certain segments, thereby gaining a foothold in the market.
In low-end disruption, the disruptor is focused initially on serving the least profitable customer, who is happy with a good enough product. This type of customer is not willing to pay premium for enhancements in product functionality. Once the disruptor has gained foot hold in this customer segment, it seeks to improve its profit margin. To get higher profit margins, the disruptor needs to enter the segment where the customer is willing to pay a little more for higher quality. To ensure this quality in its product, the disruptor needs to innovate. The incumbent will not do much to retain its share in a not so profitable segment, and will move up-market and focus on its more attractive customers. After a number of such encounters, the incumbent is squeezed into smaller markets than it was previously serving. And then finally the disruptive technology meets the demands of the most profitable segment and drives the established company out of the market.
"New market disruption" occurs when a product fits a new or emerging market segment that is not being served by existing incumbents in the industry. The Linux operating system (OS) when introduced was inferior in performance to other server operating systems like Unix and Windows NT. But the Linux OS is inexpensive compared to other server operating systems. After years of improvements it threatens to displace the leading commercial UNIX distributions.