If you search on the phrase “killer app”, you will find a definition along the lines of a feature, function, or application of a new technology or product that is presented as virtually indispensable. The two essential components of the killer app being: 1. Competitive features and function 2. Indispensability Before diving into the healthcare part of this, it is worth mentioning one of the all-time great killer apps in consumer technology: The Sony Walkman.