Smoothers, or smoothing filters, are algorithms for time-series processing that reduce abrupt changes in the time-series and make it look smoother. Smoothers constitute a broad subclass of filters. Like all filters, smoothers may be subdivided into linear and nonlinear. Linear filters reduce the power of higher frequencies in the spectrum and preserve the power of lower frequencies.
Besides time series processing, there are various smoothers for processing of images (2-dimensional objects) and spatial fields (2 and 3-dimensional objects).