: Mobile processors form a large and very fast growing segment of semiconductor market. Although they are used in a great variety of embedded systems such as personal digital organizers (PDAs), smart cards, internet appliances, laptops, smart badges, cellular phones, wearable computers, and sensor networks, they share the common need for low power, code density, security, cost sensitivity and multimedia and communication processing. The goal of this paper is to review the field of processors for mobile applications. We survey a spectrum of processors, their system software, and the accompanying hardware components. The emphasis is on classification and identification of major technology and architecture trends. Companion to this paper is a WWW page [Mob00], which provides comprehensive additional material about mobile processors.