Although there are several ways that noise can be coupled through a system including: electrical and magnetic induction, radiated coupling, and conducted coupling, this presentation deals primarily with magnetic components used for suppressing conducted noise. In general there are two types of conducted noise, differential and common mode, and each type requires a different filtering solution. The top diagram here shows a sketch of a power supply including the source and the load and shown, in green, the power supply current circulating through the system. The middle diagram shows the same sketch but this time with the differential mode noise current shown in red. Differential mode noise travels along the line and returns through the neutral. The bottom diagram again shows the same sketch, but this time with the common mode noise current shown in purple. Common mode noise travels along both line and neutral in the same direction and then returns through ground via parasitic elements within the system.