Selecting the right switch technology (in terms of RF performance, reliability, switching time, power handling, etc.) to accessorize and/or complement your system set-up requires an investment of time and resources. This application note will not only enhance your core knowledge of the various switch technologies, but will also provide a selection of products currently offered by Keysight Technologies, Inc. to serve as a platform of comparisons for the technologies explained. The two mainstream switch technologies in use today, namely solid state and electro-mechanical (EM), will be discussed. The primary focus will be on the theory of operation, coupled with detailed explanation on some of the typical performance details.