T~e aim of .th~s article is to acqu.ain~statisticians and practitioners, whose research activities require statistical methodology, With th~statistical. theory and apphc~tlons~f Walsh-Fourier analysis. It has been suggested that Walsh spectral analysis is suited t~(albe.lt~~t restricted .to) the analysis of discrete-valued and categorical-valued time series, and of time series that contain sharp dlscon~n.U1tIes. I explain~he need for Walsh-Fourier analysis, review the history and properties of Walsh functions, and outline the existmg .Walsh-Founer theory. for real-time stationary time series. I discuss various statistical applications based on the Walsh-Founer transform and provide an annotated bibliography.