Clayton Christensen, Sally Aaron and WilliamClark, focus on the effects of disruptive technology that change competition in their field. Christensen's theory, developed in the corporate realm, is based on the constant pursuit of excellence by both businesses and higher education institutions. As the quality of products increases, they often surpass the needs of their consumers, leaving a gap to be filled by a disruptive innovation (a product or service of lower quality or performance that more closely matches consumers' needs). Other features make the innovation appealing as well, such as being cheaper, simpler, and more convenient to use. Early adopters of the disruptive technology or service most often are the least demanding customers in a market.