Ferrite core is a commonly type of interference supression component used in electronic circuit, mostly it's made from Ni-Zn or Mn-Zn ferrite which are economical in cost. Ferrite core performs different impedance properties at different frequency conditions, generally it remains small impedance in low frequanecy range, and with frequency increasing, the impedance will goes up rapidly until to the peak value. 

In practical application, the higher the frequency is, the more likely the signal could radiate away, so the signal line will receive different high frequency radiations which disturb useful signals. In this condition, adopting ferrite cores can efficiently suppress the disturbing signals and keep the right signals going through normally.