Different types of stylus are used for resistive and capacitive touchscreens. Touchpads operate in one of several ways, including capacitive sensing and resistive touchscreen. It is the first mobile phone with a capacitive touchscreen. Linear encoder technologies include optical, magnetic, inductive, capacitive and eddy current. Ultrasonics, typically refers to piezoelectric transducers or capacitive transducers. Tactile sensors may be of different types including piezoresistive, piezoelectric, capacitive and elastoresistive sensors. Rarely, capacitive or inductive pressure sensors are used. Capacitive sensors can also replace mechanical buttons. There are four basic coupling mechanisms&colon; conductive, capacitive, magnetic or inductive, and radiative. Human interface devices based on capacitive sensing, such as trackpads, can replace the computer mouse. There are two general types of capacitive displacement sensing systems. One of the more common applications of capacitive sensors is for precision positioning. Likewise capacitive or inductive networks are one-element-kind. These inductive or capacitive pieces of metal are called stubs. In circuits with primarily capacitive loads, current leads the voltage.