The document discusses disruptive technology theory. It defines a disruptive technology as one that displaces an established technology and transforms an industry. Harvard professor Clayton Christensen coined the term and categorized new technologies as either sustaining or disruptive. Disruptive technologies lack refinement initially and appeal to a limited audience but may eventually displace existing technologies. Examples provided include the personal computer displacing typewriters, Windows enabling personal computing, email displacing letters, and cell phones disrupting telecoms.