High pass filter

High pass filter works only on high frequency signals. it is exact opposite to low pass filter

this is the simple RC high pass filter. it consists of two components resistor and capacitor. if low frequency signal is applied, the reactance of the capacitor is high.(reactance of the capacitor is inversely proportional to the frequency). so the capacitor acts like a open circuit.
if high frequency signal is applied. the reactance of the capacitor is low. so the capacitor acts like a short circuit.