The Gaussian blur filter has the effect of blurring an image. It is a popular filter effect that is used to reduce image noise and detail. It is a convolution that uses a Gaussian kernel to blur the image pixels.
You can specify the kernel size (the height and width of the array of pixels to consider) and the Sigma (the standard deviation for the Gaussian function used the calculate the kernel).
Gaussian blurring can have a dramatic effect on the resulting image and can make it virtually useless (other than for artistic purposes). However, it can also reduce noise in the resulting image.
A technique that may have merit for some images involves blurring an image before and/or after sharpening it in an effort to reduce artifacts.