An increasing amount of electric energy is consumed by computers as they progress in function and capabilities. All of it is dissipated in heat during the computing and communicating operations and we reached the point that further developments are hindered by the unbearable amount of heat produced. In this paper, we briefly review the fundamental limits in energy dissipation, as imposed by the laws of physics, with specific reference to computing and memory storage activities. Different from previous approaches, we will focus on the sole dynamics of the binary switches, the building blocks of the logic gates and digital memories, without invoking any direct connection to the notion of information.