Thermal management of modern electronics has become a problem of significant interest due to the demand for power and reduction in packaging size. The focus of this paper is to present a general overview of the main kinds of the micro heat pipes used in cooling the electronic devices nowadays, and their applications. Flat heat pipes are typically used for cooling printed circuit boards or for heat levelling to produce an isothermal plane. The newest is the use of a "heat-pipe heat spreader" embedded in a silicon substrate as an alternative to the conductive cooling of integrated circuits using diamond films.