High frequency signal switch
A switch made from a single MOSFET or a pair driven with complementary signals (a transmission gate) will have capacitance between input and output, capacitance to the supply rails, and capacitance between the control line and input and output. The capacitance between the control line and the switch is often characterized as "charge injection". 

It will also have leakage when off and will have resistance when on. The resistance when on will be modulated with the input voltage, which will generally cause distortion in the output.