Recently, the increasing use of power electronic systems and time‐variant nonlinear loads has brought number of power harmonics/interharmonics, and the power supply quality is therefore seriously threatened. The presence of interharmonics strongly poses more difficulties in modelling and measuring the distorted waveforms. Therefore, this paper reviews the sources, effects, and modelling of interharmonics. It provides a variety of crucial phenomena caused by interharmonics. More importantly, it also gives a possible solution for engineers/researchers to use appropriate tools to measure interharmonics. Some methods with implementation results are introduced and discussed for details.