Twenty years after the introduction of the theory, we revisit what it does—and doesn’t—explain. by Clayton M. Christensen, Michael E. Raynor and Rory McDonald Please enjoy this HBR Classic. Clayton M.

But Why is a show led by kids. They ask the questions and we find the answers. It’s a big interesting world out there. On But Why, we tackle topics large and small, about nature, words, even the end ...

Anxiety is both a mental and physical state of negative expectation. Mentally it is characterized by increased arousal and apprehension tortured into distressing worry, and physically by unpleasant ...